Assessment of emergency core cooling system effectiveness for light water nuclear power reactors

The effectiveness of Emergency Core Cooling Systems (ECCS) for light water nuclear power reactors was the subject of lengthy, controversial and technically complex hearings conducted by the AEC over the two years from 1971 through 1973. An independent, objective review and assessment of the technical issues associated with ECCS effectiveness was conducted in a study performed at the Environmental Quality Laboratory of the California Institute of Technology. The review was based upon the testimonies and supporting technical documentation of the principal participants in the hearings: the AEC, utilities, reactor manufacturers, and intervenors. From the review, the critical technical parameters influencing ECCS performance, which were at issue, are identified. Of fifteen parameters cited by the Advisory Committee on Reactor Safety in the hearings as being of unproved conservatism, essentially all are reviewed in detail, including, for example, the initial stored fuel energy, fuel rod gas gap conductance, fluid flow rates through broken pipes, metal-water reaction energy release and fuel rod embrittlement, reflood/core-spray heat transfer, and reflooding rates, as well as the adequacy of ECCS analytical models and numerical methods. ,The relative influence of uncertainties in the performance criteria associated with these parameters is assessed. Based upon the relative importance of these parameters, alternative responses to resolution of the ECCS problem are analyzed. The importance of the core reflooding rate in resolving the technical issues of the problem is emphasized. The conservatism of the proposed criteria (current and past) is reviewed. Recommendations are made for improvements in criteria conservatism, especially in the establishment of minimum reflood heat transfer rates (or alternatively, reflooding rates). Several new and/or accelerated research programs and additional large scale testing programs are also recommended. Suggestions are also made for areas in which design improvements would help to achieve greater ECCS reliability

User guide for the British Geological Survey Blockfields dataset

This report presents a description of the Blockfields dataset developed by the British Geological Survey (BGS). The dataset provides screening-level data that gives an indication of the geological suitability of the subsurface for the presence of blockfields. The dataset is designed to be used by those involved in the strategic assessment of the subsurface for the management or development of sites in Great Britain. It may be particularly valuable for spatial planners and local authorities who wish to undertake a strategic assessment. The dataset is derived from a combination of BGS national datasets and the DTM of Great Britain at 5m resolution © Bluesky International Limited elevation data to show the environmental suitability for blockfield presence in Great Britain. The approach was developed by geologists using basic landscape characteristics from a large sample of observed blockfields, and implemented by specialists in geologically derived products at BGS. The purpose of this user guide is to enable those licensing this dataset to have a better appreciation of how this dataset has been created and therefore gain a better understanding of its potential applications and limitations

Solvatochromism in Perylene Diimides; Experiment and Theory

We report an experimental and computational investigation into the solvatochromism of a perylene diimide derivative. The alkyl swallowtail substituents allowed solubility in many solvents of widely differing polarity, with a complicated resultant behaviour, illustrating both negative and positive solvatochromism as a function of dielectric constant. Luminescence quantum yield and optical absorption linewidth displayed an inverse correlation, indicating varying degrees of intermolecular aggregation, and a remarkably similar trend was found between the peak absorption wavelength and the solvent boiling point, illustrating the dependency of aggregation on the solvent interactions. These outline trends may be parameterised by an empirically derived dimensionless quantity, as a tool to be used in more sophisticated future models of solvatochromism in small molecule chromophoresPeer reviewe

Analysis of Milk Powder by Direct Nebulization into Inductively-coupled Plasma

Sample preparation has always been a tedious but important step in analysis involving Inductively Coupled plasma emission spectrometry. In addition, it may also be a source of sample contamination. The present work attempts to overcome these problems by nebulizing milk powder suspensions directly into the plasma. Various infant and full cream milk powders were dispersed in water as well as 0.5% triton-X solution. The suspensions were then analysed for calcium, phosphorus, iron, magnesium and sodium. These elements were successfully determined using inorganic standards with the addition of an internal standard to correct for the difference in viscosities

Is the Scottish population living dangerously? Prevalence of multiple risk factors: the Scottish Health Survey 2003

<b>Background:</b> Risk factors are often considered individually, we aimed to investigate the prevalence of combinations of multiple behavioural risk factors and their association with socioeconomic determinants.<p></p> <b>Methods:</b> Multinomial logistic regression was used to model the associations between socioeconomic factors and multiple risk factors from data in the Scottish Health Survey 2003. Prevalence of five main behavioural risk factors - smoking alcohol, diet, overweight/obesity, and physical inactivity, and the odds in relation to demographic, individual and area socioeconomic factors.<p></p> <b>Results:</b> Full data were available on 6,574 subjects (80.7% of the survey sample). Nearly the whole adult population (97.5%) reported to have at least one behavioural risk factor; while 55% have three or more risk factors; and nearly 20% have four or all five risk factors. The most important determinants for having four or five multiple risk factors were low educational attainment which conferred around a 3-fold increased odds compared to high education; and residence in the most deprived communities (relative to least deprived) which had greater than 3-fold increased odds.<p></p> <b>Conclusions:</b> The prevalence of multiple behavioural risk factors was high and the prevalence of absence of all risk factors very low. These behavioural patterns were socioeconomically determined. Policy to address factors needs to be joined up and better consider underlying socioeconomic circumstances.<p></p&gt

Hydrogen bonded complexes between nitrogen dioxide, nitric acid, nitrous acid and water with SiH3OH and Si(OH)4

The inter-conversion of nitrogen oxides and oxy acids on silica surfaces is of major atmospheric importance. As a preliminary step towards rationalising experimental observations, and understanding the mechanisms behind such reactions we have looked at the binding energies of NO2, N2O4, HNO3, HONO and H2O with simple proxies of a silica surface, namely SiH3OH and Si(OH)4 units. The geometries of these molecular clusters were optimised at both HF/6-311+G(d) and B3LYP/6-311+G(d) level of theory. The SCF energies of the species were determined at the HF/6-311++G(3df,2pd) and B3LYP/6-311++G(3df,2pd) level. The values indicate that nitric acid is by far the most strongly bound species, in agreement with experimental observations. It was also found that the dimer N2O4 is significantly more strongly bound to the Si(OH)4 and SiH3OH units than NO2 itself. The vibrational frequencies calculated for the hydrogen-bonded complexes are compared to the experimentally observed frequencies of the adsorbed species where possible

Carabid and Staphylinid beetles from agricultural land in the lower Fraser Valley, British Columbia

Pit-traps were emptied every two or three days for two seasons in crop, fallow, and grass plots to determine the species and population density of Carabidae and Staphylinidae associated with agricultural land, and their relationship with brassica crops. Half of the plots were enclosed by plastic barriers and the beetles were trapped to extinction: half were not enclosed. Thirty-three carabid and 16 staphylinid species were captured. The dominant species was the small, generalized. European carabid predator, <i>Bembidion lampros</i>, which had a population on crop and fallow land of about 29000/hectare. It was almost absent in grass. Other numerous carabids were <i>Harpalus aeneus</i>, <i>Calathus fuscipes</i>, and <i>Clivina fossor</i>, all introduced European spp., with populations of almost 2000, 5600, and llOOO/hectare respectively. The first and third of these were scarce in grassland but the second was abundant. In plots of Brussels sprouts <i>Aleochara bilineata</i>, a staphylinid, was effectively parasitic on root maggots, and averaged more than 6000/hectare. Soil cores taken in October centred on a Brussels sprouts plant averaged 26.4 <i>Hylemya puparia</i> per core of which 44% were parasitized by <i>A. bilineata</i>

Easing the transition from secondary school to higher education through recognition of the skills of our students

This short communication discusses research, which has investigated students‟ self-perception of their skills. This was to identify which skills they felt most and least confident in upon starting university. General and scientific and practical skills as well as skills related to improving learning were explored. The results suggested that students felt most confident in working in groups, interacting with people to obtain the necessary information and assistance, and observing chemical events and changes among others. In contrast students felt least confident in planning and presenting an oral presentation, analysing and evaluating experimental data, and using the internet and other resources to gain information. Details of how the findings were used to make effective changes to an existing module will be discussed. Furthermore, the relevance of this in terms of supporting our first year students in their transition to university-level work and subsequently planning appropriate modules will be discussed in relation to the recently published results from the UK Physical Sciences Centre Review of the Student Learning Experience in Chemistry and in light of the Department for Business Innovation and Skills Higher Ambitions and Skills for Growth papers

Updated world map of the Köppen-Geiger climate classification

International audienceAlthough now over 100 years old, the classification of climate originally formulated by Wladimir Köppen and modified by his collaborators and successors, is still in widespread use. It is widely used in teaching school and undergraduate courses on climate. It is also still in regular use by researchers across a range of disciplines as a basis for climatic regionalisation of variables and for assessing the output of global climate models. Here we have produced a new global map of climate using the Köppen-Geiger system based on a large global data set of long-term monthly precipitation and temperature station time series. Climatic variables used in the Köppen-Geiger system were calculated at each station and interpolated between stations using a two-dimensional (latitude and longitude) thin-plate spline with tension onto a 0.1°×0.1° grid for each continent. We discuss some problems in dealing with sites that are not uniquely classified into one climate type by the Köppen-Geiger system and assess the outcomes on a continent by continent basis. Globally the most common climate type by land area is BWh (14.2%, Hot desert) followed by Aw (11.5%, Tropical savannah). The updated world Köppen-Geiger climate map is freely available electronically in the Supplementary Material Section