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A global model is proposed to simulate the drying process of used nuclear fuel assemblies under vacuum drying conditions. The transient model consists of a coupled mass and energy conservation equation with appropriate source and sink terms. The classic Hertz-Knudsen expression is employed to resolve the evaporation rate and the associated water mass depletion in the system. Both latent heat of vaporization and residual decay heat are considered as sink and source in the energy conservation, respectively. The model is employed to simulate vacuum drying of spent nuclear fuel rod storage systems. Multistage stepwise vacuuming of the system is emulated, and several parametric studies are conducted to identify their role in the drying process. The predicted temporal profiles show that the proposed model is able to capture qualitative trends of the water removal rate, hence the dryness level of the system. The model prediction is also compared against experiments where the amount of residual water after a standard vacuum drying procedure is quantified. The predictions are found to compare favorably with the experimental measurements. [ABSTRACT FROM AUTHOR]

The literature in the West points to the emergence of old age care settings for LGBTI elders. However, the experiences of LGBTI elders in South Africa points towards the need to trouble a range of concepts that are Western in origin and context specific. Constructs such as 'aging', 'old age', and 'elder care' have historical and sociopolitical contours that are not universal. For example, while old age 'homes' may be a part of the life course experience in the West, in the South African context, LGBTI elders reject the notion of elder care in residential home settings. In the South African context, age is also associated with strength and agency, and LGBTI elders report coping strategies as they age. From these strategies emerge clear recommendations in terms of Afrocentric strategies in relation to LGBT elder social inclusion and support. This study explored experiences of aging and care in the Western Cape and Gauteng and utilised a qualitative method where four focus groups were facilitated with 22 LGBT elders. These included 11 from the Western Cape and 11 in Gauteng. The majority were gay men, and the age range was between 50 and 75 years. In Gauteng most of the participants were coloured (of mixed descent) whereas in the Western Cape there was a mix of races. [ABSTRACT FROM AUTHOR]

The large share of carbon emitted by energy-intensive industries in the extraction and processing of basic materials must be limited to decarbonise society and the economy. Ways in which the state can govern industrial decarbonisation and contributes to green state theory are explored by addressing a largely ignored issue: the green state's industrial relations and its role in industrial governance. With insights from a Swedish case study, the tension between the state's economic imperative and ecological concerns in greening industry are shown to persist. However, as the energy-intensive industry's previously privileged position in the economy is weakening, industry is opened to decarbonisation strategies. While the case exposes a number of governance challenges, it also suggests potential areas where the state can pursue decarbonisation in energy-intensive industry and points the way to an active role of the green state in governing industrial decarbonisation and greening industry. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editors discuss various reports within the issue on topics including urban planning, urban renewal and urban land use.

Colonization of HVAC systems by microbes may lead to release of hazardous bioaerosols containing allergens, irritants, odorants, or infectious agents to indoor air, possibly adversely affecting system performance. Unlike the many common materials used in HVAC systems, copper and copper alloys have been shown in laboratory investigations to kill bacteria and fungi on contact after several hours. This study tested copper's antimicrobial properties in comparison with aluminum in full-scale, carefully controlled air-conditioning systems, four with copper heat exchanger assemblies and four with aluminum assemblies, at identical airflow rates, temperatures, humidity, and input microbe levels. Fungal and bacterial loads on copper surfaces in heat exchangers were lower than on aluminum surfaces by factors of 3500 and more than 500, respectively, over a 4-month period. No statistically significant difference in the release of airborne microbes was detected between copper and aluminum heat exchangers. The moderate conditions employed in this study, while still within the range commonly found in HVAC systems, possibly prevented the high microbial loading on aluminum heat exchanger surfaces from translating into significant differences in airborne concentrations between copper and aluminum systems. [ABSTRACT FROM AUTHOR]

This comparison of the effects of national approaches to encouraging local climate mitigation initiatives in four municipalities in Norway and Sweden suggests that the development of such initiatives depend not only on the comprehensiveness and ambitions of central government efforts, but more crucially on characteristics of the targeted municipalities. We argue that local coalitions of committed individuals forming implementation structures of varying cohesiveness are important for understanding variations in the effects of government programmes on the development of local mitigation initiatives. [ABSTRACT FROM AUTHOR]

The thermal conductivity of the fuel in today's light water reactors, uranium dioxide (UO2), can be improved by incorporating a uniformly distributed heat-conducting network of a higher-conductivity material: silicon carbide (SIC). The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 (97% theoretical density). This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and development of a formal methodology for producing the resultant composite oxide fuel. Calculations of the effective thermal conductivity (ETC) of the new fuel as a function of percent SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The ETCs are obtained at different temperatures from 600 to 1600 K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. The heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for the thermal conductivity calculations and to estimate the reduction in centerline temperatures achievable within such a fuel rod. Later, the computer codes COMBINE-PC and VENTURE-PC were employed to estimate the fuel enrichment required to maintain the same burnup levels corresponding to a volume percent addition of SiC. [ABSTRACT FROM AUTHOR]

The impact of a worker's location, orientation, and activity was studied in an experimental room (2.86 m × 2.35 m × 2.86 m) at known flow rates of 5.5 m3/min and 3.3 m3/min. A person in the room, wearing a full-facepiece, air-supplied respirator represented a worker. Propylene tracer gas was emitted at a constant rate from a 1-m pedestal at the center of the room and a continuous air sample was drawn from a point midway between the worker's mouth and nose. Breathing zone concentration (BZC) was monitored at 12 worker locations within the room for a stationary worker. At each location, BZCs were measured separately for four worker orientations: east, west, south, and north. BZCs of a walking worker were also monitored along the path defined by the 12 worker locations used in the stationary experiments. In a separate set of experiments, area concentration was monitored to see whether the worker's activity disturbed the contaminant concentrations at a fixed sampling point located behind the source looking from the direction of air inlet (location: 1.34 m, 1.20 m, 0.45 m). The following average differences in BZC over the 12 fixed locations were observed: 43% higher for near-field than for far-field locations; 20% higher when the worker was facing the source than when facing away (p-values for all four conditions: < 0.033), and 30% higher for a moving worker than for a stationary worker (p-values for all four conditions: < 0.01). When the worker was walking, the concentration at the fixed area sampling point was generally lower than the area concentration when the worker was absent or stationary in the room, possibly due to greater mixing of room air by the worker's movement. Because a worker's activities may be irregular and complicated, incorporating them as parameters in mathematical models is often not feasible. Instead, these findings may be used to assess uncertainty or adjust exposure estimates from simple models. [ABSTRACT FROM AUTHOR]

The planning of facilities to improve the environment is often carried through in the form of locally based construction projects. These projects can be complex, involving a variety of issues and a number of different actors from both the public and private sectors. By drawing on previous research on project planning, an analytical model for analysing the issues connected with the planning and implementation of environmental projects is developed. The main argument of the paper is the importance of considering how context-specific factors affect project design and project management. The empirical material is taken from the planning of two biogas projects in Sweden and it is showed how differences in factors such as the actors involved, the organisational framework and the political setting lead to two markedly distinct planning approaches. The results of the paper, which also highlight the importance of a flexible planning approach, are relevant not only for biogas but also for other projects with similar characteristics. [ABSTRACT FROM AUTHOR]

Compares emission models with computational fluid dynamic simulation. Importance in understanding source behavior in controlling exposure to airborne contaminants; Computation of room airflow and concentration fields using Fluent 4; Assessment of plausible concentration fields; Definition of error.

The aim of the paper is to compare the planning for wind power in three municipalities and analyze how it has influenced three important aspects of the wind power development: the siting of turbines, the ownership of turbines and citizen participation. The paper shows that the planning strategies of the municipalities differed considerably and that this in turn has led to differences in the development of wind power. A general conclusion is that there seems to be a dilemma in municipal planning between, on the one hand, the promotion of wind power and, on the other hand, the organization of a planning that effectively regulates the siting of turbines and allows for citizen participation. The results show that there is a need to support and strengthen municipal planning capacities, and efforts in that direction are being undertaken by state and regional authorities in Sweden. The results, however, also imply the need for stronger policy measures in order to avoid large differences between the way wind power is handled at the municipal level. [ABSTRACT FROM AUTHOR]

In specifying dilution ventilation flow rate, a safety factor, K, is often used to provide a margin of safety and to compensate for uncertainties and health impact severity. In current practice, the selection of K is very subjective. Here the component of K accounting for imperfect mixing, K[sub m], was studied to develop more effective and efficient design procedures. Air flow and contaminant distribution in a 10 m × 3 m × 7 m room with a single contaminant source on a 1-m high table were simulated for steady, isothermal conditions using computational fluid dynamics. A series of 10 simulations explored factorial combinations of air exchange rates (1, 2, 4, 8, 16 ACH) and inlet types (a high wall jet and a ceiling diffuser). Nine additional simulations explored exhaust opening location effects and 13 other simulations investigated source location effects. K[sub m] was calculated at each of 25,600 grid locations within the room by linear regression of emission rate/flow rate (G/Q) on concentration (C). The linear relationship between C and G/Q at each of the points was nearly perfect (R[sup 2] ≥ 0.97). For the simulations with varying dilution flow rate, K[sub m] ranged from 0.19 to 2.86 for the wall jet and from 0.94 to 4.34 for the ceiling diffuser. Holding G/Q at 100 ppm and varying source and exhaust location produced room average concentrations from 55.7 to 173 ppm. Unlike orthodox design approaches, this work suggests that air monitoring data often can be used to calculate dilution flow rate requirements. Also, dilution flow rate requirements may be reduced by enhancing room mixing with fans or altering air inlet configuration. However, mixing should not be increased if the altered room air currents could transport contaminant to an occupant's breathing zone or interfere with other control methods that depend on segregation of incoming air and contaminant. [ABSTRACT FROM AUTHOR]

This paper develops a model to predict the nugget development during resistance spot welding (RSW) of Al-alloys. The model employs a coupled thermal-electrical-mechanical analysis and accounts for phase change and convective transport in the weld pool. The contact area and the pressure distribution are determined from a coupled thermal – mechanical model. The model calculates time varying interface pressure. The knowledge of interface pressure allows for accurate prediction of interfacial heat generation. Temperature-dependent thermal-electrical-mechanical properties are used. The predicted nugget shape and size agree well with experimental data. The proposed model can be applied to predict the effects of the welding parameters and the electrode shapes on the nugget development. [ABSTRACT FROM AUTHOR]

For many years exposure to airborne contaminants has been estimated by air or biological monitoring. In occupational settings, mathematical models increasingly are employed as adjuncts to monitoring, for instance, during process design or in retrospective epidemiological studies. Models can make predictions in a wide variety of scenarios, can be used for rapid screening, and may reduce the need for monitoring in exposure assessment. However, models make simplifying assumptions regarding air flow and contaminant transport. The errors resulting from these assumptions have not been systematically evaluated. Here we compare exposure estimates from the single-zone completely mixed (CM-1), two-zone completely mixed (CM-2), and uniform diffusivity (UD) models with workroom concentration fields predicted by computational fluid dynamics (CFD). The room air flow, concentration fields, and the breathing zone concentration of a stationary worker were computed using Fluent V4.3 for factorial combinations of three source locations, three dilution air flow rates and two emission rate profiles, constant and time-varying. These numerical experiments were used to generate plausible concentration fields, not to simulate exactly the processes in a real workroom. Thus, ''error'' is defined here as difference between model and CFD predictions. For both constant and time-varying emission sources, exposure estimates depended on receptor and source location. For the constant source case, ventilation rate was shown to be inconsequential to CM-1 model error. CM-1, CM-2, and UD models differed in their agreement with CFD. UD was closest to CFD for estimating concentration in the simulated breathing zone (BZ) near the source, although large errors resulted when the model was applied to the plane of possible breathing zones. CM-1 performed better for this plane but underestimated the near-source BZ exposure. For the near-source BZ location, CM-2 replicated CFD predictions more closely than CM-1 did, but less closely than UD did. Error in CM-1 model estimation of short-term average exposure to a time-varying source was highly dependent on ventilation rate. Error decreased as ventilation rate increased. [ABSTRACT FROM AUTHOR]