Evaluation of dispersion models DIPCOT and RIMPUFF used in Decision Support Systems for nuclear and radiological emergency response

This paper presents evaluation of the atmospheric dispersion models DIPCOT and RIMPUFF which are incorporated for operational use in Decision Support Systems for nuclear emergencies. The evaluation is performed through comparisons of model results with real-scale measurements of gamma radiation dose rates in air obtained during the routine operation of the HIFAR Research Reactor located in Sydney, Australia. The area surrounding the reactor is characterized by moderately complicated topography and varying land cover. A total of 16 days have been computationally simulated, covering all atmospheric stability conditions. Qualitative and quantitative model evaluation is carried out, using comparisons of paired in space and time calculated and measured gamma dose rates, statistical indices, scatter plots, and contour plots. The models performance is satisfactory for a number of cases, while for others the performance is poor. This can be attributed to a number of factors, mainly uncertainties in the prediction of meteorological conditions

Radiation source rate estimation through data assimilation of gamma dose rate measurements for operational nuclear emergency response systems

This paper presents an evaluation of an innovative data assimilation method that has been recently developed in NCSR Demokritos for estimating an unknown emission rate of radionuclides in the atmosphere, with real-scale experimental data. The efficient algorithm is based on the assimilation of gamma dose rate measured data in the Lagrangian atmospheric dispersion model DIPCOT and uses variational principles. The DIPCOT model is used in the framework of the nuclear emergency response system (ERS) RODOS. The evaluation is performed by computational simulations of dispersion of Ar-41 that was emitted routinely by the Australian Nuclear Science and Technology Organisation’s (ANSTO) previous research reactor, HIFAR, located in Sydney, Australia. In this paper the algorithm is evaluated against a more complicated Radiation source rate estimation through data assimilation 387 case than the others used in previous studies: There was only one monitoring station available each day and the site topography is characterised as moderately complex. Overall the estimated release rate approaches the real one to a very satisfactory degree as revealed by the statistical indicators of errors. © 2012 Inderscience Enterprises Ltd

One-year intensive characterization on PM2.5 nearby port area of Thessaloniki, Greece

The chemical characterization of particulate matter (PM) 2.5 fraction was studied during a 1-year sampling campaign conducted at a site near Thessaloniki’s port area. PM2.5 collected samples were chemically analyzed for polycyclic aromatic hydrocarbons, minerals, and trace elements (Pb, Ni, Cu, V, Mn, Cr, Zn, Mg, K, Ti, Fe, Ca, and Al); water-soluble ions (Cl−, NO3−, SO42−, K+, Na+, NH4+, Mg2+, Ca2+); and organic and elemental carbon. The average annual PM2.5 concentration (66.0 μg/m3) was at the highest level compared with other studies reported for the same city but different sampling sites. The average daily sum of the measured concentration of polycyclic aromatic hydrocarbons (PAHs) was 12.76 ng/m3; this value decreased to 6.73 ng/m3 for the warm period and reached the value of 19.8 ng/m3 for the cold period. The average concentration of benzo[a]pyrene during the sampling period was 0.75 ng/m3, which is below the European Union limit value of 1.0 ng/m3. The ionic content comprised, on average, 22.6 % of the PM2.5 mass, with sulfate and ammonium being the most abundant species (31 and 26 %, respectively, of measured ions during the whole sampling period). The annual mean concentrations of organic carbon (OC) and elemental carbon (EC) were 10.5 ± 6.3 and 2.3 ± 1.5 μg/m3, respectively. The OC/EC ratio ranged from 1.6 to 9.9, suggesting that there is a significant influence of residential wood burning for heating as well as ship and vehicle emissions to the sampling area. Finally, the elemental composition of associated PM2.5 was dominated by Ca, Fe, and Al. Although conclusions based only on PM2.5 measurements cannot entirely estimate all harbor sources’ contribution, there is evidence to support that port activities affect the city’s air quality and vice versa

The SMEDIS database and validation exercise

SMEDIS is an ongoing research project funded by the European Union under the Environment and Climate Research Programme for the period 1996-1999. The project is coordinated by the Health and Safety Executive (HSE, UK) with two other main partners: Cambridge Environmental Research Consultants (CERC, UK) and Electricité de France (EDF, France). Ten additional partners from across Europe are also participants in the project. The main objective of the project is to develop a methodology for the evaluation of dense gas atmospheric dispersion models used in the study of accidental releases of explosive or toxic materials. This evaluation is composed of a scientific assessment of each model, together with a validation by comparison with available experimental data. This paper describes more specifically the database constructed, and the validation performed by the participants involved in the project. Preliminary results indicate that the restriction for arcwise concentrations leads to an optimistic view of model performance when complex effects are present and that, in general, statistical performance is better for more sophisticated models

Perceived indoor environment and occupants’ comfort in European “modern” office buildings: The OFFICAIR study

Indoor environmental conditions (thermal, noise, light, and indoor air quality) may affectworkers’ comfort, and consequently their health and well-being, as well as their productivity.This study aimed to assess the relations between perceived indoor environment and occupants’comfort, and to examine the modifying effects of both personal and building characteristics.Within the framework of the European project OFFICAIR, a questionnaire survey was administered to7441 workers in 167 “modern” office buildings in eight European countries (Finland, France, Greece,Hungary, Italy, The Netherlands, Portugal, and Spain). Occupants assessed indoor environmentalquality (IEQ) using both crude IEQ items (satisfaction with thermal comfort, noise, light, and indoorair quality), and detailed items related to indoor environmental parameters (e.g., too hot/coldtemperature, humid/dry air, noise inside/outside, natural/artificial light, odor) of their officeenvironment. Ordinal logistic regression analyses were performed to assess the relations betweenperceived IEQ and occupants’ comfort. The highest association with occupants’ overall comfort wasfound for “noise”, followed by “air quality”, “light” and “thermal” satisfaction. Analysis of detailedparameters revealed that “noise inside the buildings” was highly associated with occupants’ overallcomfort. “Layout of the offices” was the next parameter highly associated with overall comfort.The relations between IEQ and comfort differed by personal characteristics (gender, age, and theEffort Reward Imbalance index), and building characteristics (office type and building’s location).Workplace design should take into account both occupant and the building characteristics in order toprovide healthier and more comfortable conditions to their occupants.Indoor Environmen