4,346 research outputs found
Monte Carlo Calculation of the Power Distribution in the PDS-xADS at BoL and EoL E. Nava, K. W. Burn - (FIS - NUC)
No full textThis document is part of the Deliverable D49 ('Core Reference Cycle Analysis for the LBE-Cooled XADS') for Work Package N. 4.1, in the framework of PDS-XADS (preliminary Design Studies of an Experimental Accelerator-Driven System) project. This report is devoted to the evaluation of the power distribution in the core at the Beginning of Life (BoL) and End of Life (EoL). The results have been passed to FZK far evaluation of the thermohydraulics characteristics
Contractual Deliverable D49 (WP4.1) Core Reference Cycle Analysis far the LBE-Cooled XADS K. W. Burn, G. Glinatsis, E. Nava, V. Peluso, C. Petrovich, M. Sarotto, R. Tinti (FIS-NUC)
No full textThis document is the Deliverable D49 for Work Package N. 4.1 (in the framework of PDSXADS: Preliminary Design Studies of an Experimental Acce1erator-Driven System), which analyzes the core reference cyc1e for a LBE (lead bismuth eutectic) cooled core coupled with a LBE windowless target. It is ordered in terms of stand-alone work units with a synopsis summarizing each unit
Learning Aspects of the Direct Statistical Approach to the Optimization of Monte Carlo Radiation Transport Calculations
No full textUse of an Innovative Monte Carlo Technique to Calculate Neutron Spectra in BNCT - Application to the TAPIRO Reactor
No full textThe DSA (Direct Statistical Approach) is a technique to generate optimum variance reduction parameters that govern the track population (or weight) in Monte Carlo radiation transport calculations. The DSA has recentrly been extended to multiple response problems. This development has proved particularly useful in calculating neutron flux spectra in BNCT applications
Optimization of Variance Reduction Parameters in Monte Carlo Radiation Transport Calculations to a Number of Responses of Interest
No full textOn integrating Monte Carlo calculations in and around near-critical configurations I. Methodology
No full textMonte Carlo with variance reduction (VR) is employed to calculate radiation-induced responses in a variety of fixed source problems. In eigenvalue problems, Monte Carlo is used without VR (apart from implicit capture) for in-core integral responses (keff, reactivity coefficients, burn-up effects, etc.). More differential in- or ex-core responses are either treated in the same way thus limiting the range of solvable problems, or by decoupling. We evaluate an all-Monte Carlo approach developed to calculate differential in- or ex-core responses without decoupling. The ex-core problems involve responses in a GEN III PWR. The in-core problems study the neutron flux and 96Zr(n,γ) rate at the surface of a control rod in the VERA Benchmark. Comparison is made with an empirical approach involving analog Monte Carlo in-core with VR ex-core. The paper consists of two parts: part I tests the methodology; part II compares with PWR GEN II and III ex-core decoupled results
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Burn-in policies for products having dormant states
No full textMany systems might have a long time dormant period, during which the systems are not operated. For example, most building services products are installed while a building is constructed, but they are not operated until the building is commissioned. Warranty terms for such products may cover the time starting from their installation times to the end of their warranty periods. Prior to the commissioning of the building, the building services products are protected by warranty although they are not operating. Developing optimal burn-in policies for such products is important when warranty cost is analysed. This paper considers two burn-in policies, which incur different burn-in costs, and have different burn-in effects on the products. A special case about the relationship between the failure rates of the products at the dormant state and at the operating state is presented. Numerical examples compare the mean total warranty costs of these two burn-in policies
The use of topical sodium hypochlorite in the management of Pseudomonas aeruginosa burn wound infection
No full textThe aim of the study is: 1. To undertake a meta-analysis of Pseudomonas aeruginosa burn wound infection. 2. To undertake a retrospective audit of Pseudomonas aeruginosa burn wound infection at the Red Cross War Memorial Children's Hospital. 3. To investigate the local effects of sodium hypochlorite solutions in Pseudomonas aeruginosa burn wound infection with regards to efficacy and toxicity
Pattern of Childhood Burn Injuries and their Management Outcome at Bugando Medical Centre in Northwestern Tanzania.
No full textBurn injuries constitute a major public health problem and are the leading cause of childhood morbidity and mortality worldwide. There is paucity of published data on childhood burn injuries in Tanzania, particularly the study area. This study was conducted to describe the pattern of childhood burn injuries in our local setting and to evaluate their management outcome. A cross sectional study was conducted at Bugando Medical Centre (in Northwestern Tanzania) over a 3-year period from January 2008 to December 2010. Data was collected using a pre-tested coded questionnaire and statistical analyses performed using SPSS software version 15.0. A total of 342 burned children were studied. Males were mainly affected. Children aged = 2 were the majority accounting for 45.9% of cases. Intentional burn injuries due to child abuse were reported in 2.9% of cases. Scald was the most common type of burns (56.1%). The trunk was the most commonly involved body region (57.3%). Majority of patients (48.0%) sustained superficial burns. Eight (2.3%) patients were HIV positive. Most patients (89.8%) presented to the hospital later than 24 h. The rate of burn wound infection on admission and on 10th day were 32.4% and 39.8% respectively.Staphylococcus aureus were more common on admission wound swabs, with Pseudomonas aeruginosa becoming more evident after 10th day. MRSA was detected in 19.2% of Staphylococcus aureus. Conservative treatment was performed in 87.1% of cases. Surgical treatment mainly skin grafting (65.9%) was performed in 44 (12.9%) of patients. The overall average of the length of hospital stay (LOS) was 22.12 ± 16.62 days. Mortality rate was 11.7%. Using multivariate logistic regression analysis; age of the patient, type of burn, delayed presentation, clothing ignition, %TBSA and severity of burn were found to be significantly associated with LOS (P < 0.001), whereas mortality rate was found to be independently and significantly related to the age of the patient, type of burn, HIV positive with stigmata of AIDS, CD4 count, inhalation injury, %TBSA and severity of burn (P < 0.001). Childhood burn injuries still remain a menace in our environment with virtually unacceptable high morbidity and mortality. There is need for critical appraisal of the preventive measures and management principles currently being practiced
Variance Reduction with Multiple Responses
No full textRadiation transport problems that involve high attenuation require non-analogue Monte Carlo. Non-analogue techniques (i.e. employing variance reduction (V.R.) ), conserve the first moment whilst reducing the second and consequently the variance. However, because V.R. methods employ in one form or another an estimate of the importance (adjoint flux) which is strictly linked to a particular response, they are directed at a single response. V.R. parameters appropriate to one response (in that they significantly reduce the statistical error) may not necessarily be appropriate to another; they may even raise the errors of other responses compared with their analogue values. Thus Monte Carlo may treat problems involving a high attenuation only if a single response (or a set of responses with similar importances) is of interest. Monte Carlo tends to run into trouble when more differential information is required (flux distributions in many energy groups for example). The technique presented here to optimize V.R. parameters to more than one response is based on the DSA (Direct Statistical Approach) which is of general application in that it is based on V.R. techniques that are themselves of general use: population or weight control through splitting and Russian roulette
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