Data mining reactor fuel grab load trace data to support nuclear core condition monitoring

A critical component of an advanced-gas cooled reactor (AGR) station is the graphite core. As a station ages, the graphite bricks that comprise the core can distort and may eventually crack. As the core cannot be replaced the core integrity ultimately determines the station life. Monitoring these distortions is usually restricted to the routine outages, which occur every few years, as this is the only time that the reactor core can be accessed by external sensing equipment. However, during weekly refueling activities measurements are taken from the core for protection and control purposes. It is shown in this paper that these measurements may be interpreted for condition monitoring purposes, thus potentially providing information relating to core condition on a more frequent basis. This paper describes the data-mining approach adopted to analyze this data and also describes a software system designed and implemented to support this process. The use of this software to develop a model of expected behavior based on historical data, which may highlight events containing unusual features possibly indicative of brick cracking, is also described. Finally, the implementation of this newly acquired understanding in an automated analysis system is described

Knowledge, management and intelligent decision support for protection scheme design and application in electrical power systems

The paper describes a research project carried out inconjunction with two major UK utilities, focusing on the introduction of knowledge management and intelligent decision support to the existing protection design and application processes operated within both companies. A brief overview is provided of the generic design process, and the development of the web-based Design Engineering Knowledge Application System (DEKAS). This system incorporates intelligent case based reasoning (CBR) functionality to address the knowledge management and decision support requirements of each company's design process. The perceived key benefits of DEKAS relating to the management and utilisation of the data, information and knowledge throughout the protection design process is also discussed

Empirical Study Of Tube Wave Suppression For Single Well Seismic Imaging

This report addresses the Idaho National Engineering and Environmental Laboratory's portion of a collaborative effort with Lawrence Berkeley National Laboratory and Sandia National Laboratories on a borehole seismic project called Single Well Seismic Imaging. The INEEL's role was to design, fabricate, deploy, and test a number of passive devices to suppress the energy within the borehole. This energy is generally known as tube waves. Heretofore, tube waves precluded acquisition of meaningful single-well seismic data. This report addresses the INEEL tests, theories, observations, and test results

Periodic variability of spotted M dwarfs in WTS

This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.We present an analysis of the photometric variability of M dwarfs in the WFCAM Transit Survey, selected from spectral types inferred by their WTS and SDSS colours, with periods detected using a Lomb-Scargle Periodogram Analisys. We estimate population membership of these objects from their tangential velocities and photometric parralaxes. Examples of M dwarfs with variable light curve morphologuies are found. We discuss possible causes for this and make use of models of spotted stars in our interpretation of the results

Island ordering on clean Pd(110)

High resolution low-energy electron diffraction measurements are reported that demonstrate the existence of semiordered islands on the clean Pd(110) surface. The islands are stable up to 1000 °C and are approximately 90 atoms long in the 001 direction. A simple model is presented that makes use of step-step interactions to generate the periodic island structure. This model predicts that ordered islands form below the roughening temperature if the step creation energy is small compared to the step-step interaction. A justification for this condition is given for the Pd(110) surface. © 1993 The American Physical Society

Counting matrices over finite fields with support on skew Young diagrams and complements of Rothe diagrams

We consider the problem of finding the number of matrices over a finite field with a certain rank and with support that avoids a subset of the entries. These matrices are a q-analogue of permutations with restricted positions (i.e., rook placements). For general sets of entries these numbers of matrices are not polynomials in q (Stembridge 98); however, when the set of entries is a Young diagram, the numbers, up to a power of q-1, are polynomials with nonnegative coefficients (Haglund 98). In this paper, we give a number of conditions under which these numbers are polynomials in q, or even polynomials with nonnegative integer coefficients. We extend Haglund's result to complements of skew Young diagrams, and we apply this result to the case when the set of entries is the Rothe diagram of a permutation. In particular, we give a necessary and sufficient condition on the permutation for its Rothe diagram to be the complement of a skew Young diagram up to rearrangement of rows and columns. We end by giving conjectures connecting invertible matrices whose support avoids a Rothe diagram and Poincar\'e polynomials of the strong Bruhat order.Comment: 24 pages, 9 figures, 1 tabl

A CFD-based mixing model for vegetated flows

This paper provides a CFD‐based modelling framework for predicting flow field, turbulence and mixing characteristics within vegetated environments such as ponds and wetlands. The framework has been implemented within a commercial CFD code – ANSYS Fluent 19 – via a set of user‐defined‐functions. Following the approach outlined by King et al. (2012), the standard k‐ε turbulence closure model has been modified to capture the energy transfer at the vegetation/clear flow shear interface and within the vegetation. The implementation assumes that vegetation is vertical, but non‐orthogonal flow in the horizontal plane is accounted for. Values for the drag coefficient and the mixing coefficients are estimated based on the vegetation stem diameter and density. Following Tanino and Nepf (2008), a switch has been incorporated to account for the fact that the relevant length scale changes from stem diameter to stem spacing as stem density increases. A set of model parameters is proposed, based on a re‐evaluation of previously published laboratory data and theoretical analysis. Five different experimental data sets are used to demonstrate that the model is able to predict mixing within fully‐vegetated systems and due to both vertical and horizontal shear layers. The framework was developed to provide a practical prediction tool for engineering purposes, in particular for the estimation of residence time distributions in real partially‐vegetated stormwater management ponds. Its implementation here within a commercial CFD package potentially facilitates application to complex pond geometries, including patches of different types of vegetation with different bulk stem diameter and density characteristics

Current in the light-front Bethe-Salpeter formalism II: Applications

We pursue applications of the light-front reduction of current matrix elements in the Bethe-Salpeter formalism. The normalization of the reduced wave function is derived from the covariant framework and related to non-valence probabilities using familiar Fock space projection operators. Using a simple model, we obtain expressions for generalized parton distributions that are continuous. The non-vanishing of these distributions at the crossover between kinematic regimes (where the plus component of the struck quark's momentum is equal to the plus component of the momentum transfer) is tied to higher Fock components. Moreover continuity holds due to relations between Fock components at vanishing plus momentum. Lastly we apply the light-front reduction to time-like form factors and derive expressions for the generalized distribution amplitudes in this model.Comment: 12 pages, 6 figures, RevTex

Comparison between dispersed nuclear power plants and a nuclear energy center at a hypothetical site on Kentucky Lake, Tennessee

The thermal, ecological, and social impacts of a 40-reactor NEC are compared to impacts from four 10-reactor NECs and ten 4-reactor power plants. The comparison was made for surrogate sites in western Tennessee. The surrogate site for the 40-reactor NEC is located on Kentucky Lake. A layout is postulated for ten clusters of four reactors each with 2.5-mile spacing between clusters. The plants use natural-draft cooling towers. A transmission system is proposed for delivering the power (48,000 MW) to five load centers. Comparable transmission systems are proposed for the 10-reactor NECs and the 4-reactor dispersed sites delivering power to the same load centers. (auth