Nuclear power plants such as Ringhals 4 have undertaken major investments in technical improvements during the last decade to ensure secure operating and to increase efficiency. All activity concerning nuclear processing is performed under heavy regulation and it is therefore desirable to better anticipate how changes in components or new operating guidelines will implicate the overall process. The modern nuclear reactor system operates at a level of complexity where simple math and theoretical models are not capable of performing complete process calculations. Complex numerical schemes have therefore been developed to serve as powerful tools in solving the partial differential equations that describe two-phase flow and heat transfer. One of these numerical schemes is the code TRACE (TRAC/RELAP Advanced Computational Engine) that is used in this project. The objective was to compare results from the theoretical model in TRACE for the condenser system at Ringhals 4 with actual data obtained under normal operating conditions. The main components of the condenser system is composed of condenser-pumps and drain coolers with low pressure pre-heater. The main task of these pumps is to increase the static pressure in the system while the drain cooler with the preheater’s main objective is to raise the temperature. The graphic interface SNAP (Symbolic Nuclear Analysis Package) was used to design the model with constructional drawings and internal documentation as complementary sources. The boundary conditions used are sourced from either local readings, heat- and mass balance or logged values. The analysis was broken down in three different parts with focus initially on the pump system and preheaters. For completeness, the two systems were thereafter assembled to represent the whole condenser system. Satisfactory results have been obtained considering the main objective. Also discovered was that the theoretical model has a great sensitivity with new initiating values for temperature, mass flow as well as when using different pressure conditions. The main reason for this sensitivity is believed to be found in the HEATER-component, which is used to model the preheaters shell side. This also poses questions concerning how the code handles the condensation in the HEATER-component, where film condensation and forced convection should exist. Further investigation and development are therefore required before the model can be implemented in the context of more complex flow set-ups. Some of the more direct changes that are proposed would be to lowering the valves on the HEATER-component and a complete investigation around the physical conditions for the preheaters is needed to be performed.

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A literature survey has been undertaken of the sources, levels and effects of heavy metal pollution in the urban street environment. Established techniques for the determination of heavy metal levels in urban dusts have been reviewed, and appropriate methods selected for use in the research project. Spatial and temporal variations of Cd, Cu, Pb and Zn in street dust have been investigated at a number sites. Metal loadings showed stronger spatial variation than concentrations with the greatest metal loadings occurring in the gutters and kerbsides. The results have been assessed in terms of surface type and condition, traffic loadings and antecedent weather conditions. The chemical associations of heavy metals in street dust, and their relationships to particle size have been investigated. Lead and Zn were associated mainly with carbonates and Fe-Mn oxides, whereas Cu is largely found in the organic fraction. Cadmium shows the greatest affinity for the exchangeable phase, and is therefore considered the most environmentally mobile metal studied. In addition to the studies mentioned above levels and chemical associations of heavy metals In school playground dust contaminated by paint flakes have been investigated. The levels of Pb were much higher than those previously reported. Exchangeable Pb concentrations represented a significant hazard to children playing in the area. In addition to the studies mentioned above levels and chemical associations of heavy metals In school playground dust contaminated by paint flakes have been investigated. The levels of Pb were much higher than those previously reported. Exchangeable Pb concentrations represented a significant hazard to children playing in the area. The final stage of the research project involved the operation of a sampling network to establish a mass balance for Cd, Cu, Pb and Zn within a residential urban street. Metal levels in atmospheric deposition, street sediments and runoff were monitored over an eight week period. Stormwater runoff was found to remove only a minor fraction of the metal deposited in the catchment during the sampling period.

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