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[en] Modeling and implementing fire safety for nuclear power plants is a costly activity. Because of the complexity of fire phenomenon and multiple operational procedures, it is difficult to computationally provide assurance that the mitigation methods are adequate for critical areas using current analysis methods. An economical method to provide more accurate modeling and optimize mitigation methods is needed to improve nuclear power viability. This report describes the initial investigation into modeling and simulation tools for application of fire as part of the Risk-Informed Systems Analysis (RISA), formerly Risk-Informed Safety Margin Characterization (RISMC). The report provides a framework of how 3D modeling and simulation techniques could be combined with a dynamic Probabilistic Risk Analysis (PRA) to reduce compounding conservatism present in current Fire PRA methods. Electrical Power Research Institute has analyzed current Fire PRA practices and identified the most significant contributors to risk and areas for improving analysis. This framework describes how to apply dynamic PRA and simulation methods for key contributors/scenarios, credit missing factors of manual fire suppression, and applying conditional probabilities.
[en] Power cuts have become a characteristic feature of many Sub-Saharan African economies. This paper attempts to estimate the firm level impact of power outages using panel data on firms from 15 Sub-Saharan African countries. Further, I evaluate the impact of electricity self-generation in ameliorating the effects of power outages on firm performance using a quasi-experimental approach. Results from the analysis reveal significant negative effects of electricity shortages on firm productivity, size and labor employment. Finally, contrary to the notion that self-generation may be helpful for firms during outage periods, evidence from this paper suggest that reliance on self-generation is associated with productivity losses albeit short run revenue gains. (author)
[en] The decline of biodiversity is mainly due to soil acidification and the eutrophication of the environment. Nuclear power, among all energy sources has the least rate of acidification as it produces very few pollutants like sulfur dioxide and nitrogen oxide while coal combustion is the most polluting. As for renewable energies like wind energy or solar power, they require important quantities of raw materials and the extraction of rare elements which implies the release in the environment of chemical compounds that contribute to soil acidification. Eutrophication is the increase of chemical nutrients in the soil which leads to the excessive growth of some plants at the expense of others. Agriculture and a bad management of waste waters are the main causes of eutrophication, coal industry is the fifth source of eutrophication while nuclear industry is very few involved in it. Another parameter to take into account to assess the environmental impact of an energy source is the floor space used. For instance wind energy requires from 2 to 13 m2/MWh, coal industry requires 16 to 33 m2/MWh while nuclear industry needs only 0.78 m2/MWh. Wastes is another important issue, nuclear industry produces radioactive wastes but because of the high energy density of nuclear power, they are small in terms of volumes. France, every year, produces 100 kg of hazardous wastes and only 20 g of high level radioactive wastes per capita. (A.C.)
[en] Today's nuclear power plants in Korea are primarily used to supply base-load electricity due to the insufficiency of energy resources and rapid increase of electricity demand. In compliance with the government policy, Korea Electric Power Corporation (KEPCO) established an ambitious nuclear power plant construction program. According to the expansion of the nuclear power program, it is necessary to analyse the environmental impact of nuclear power generation system. Future requirements would be the improvement of environmental impact assessment of nuclear power generation system with respect to the various environmental themes including radiological and non-radiological assessment. Life Cycle Assessment (LCA) is an appropriate methodology for this requirement. General definition of LCA is a process to evaluate the environmental burdens associated with a product, process, or activity by identifying and quantifying energy, materials used and wastes released to the environment. LCA studies the environmental aspects and the potential impact throughout a product or service's life cycle. LCA is one of several environmental management techniques and a decision support tool, i.e., LCA is not the decision result itself. However, direct introduction of LCA to the nuclear fuel cycle is difficult more or less due to the absence of the methodology for the radiological impact assessment within the LCA framework. Problems of existing method for the toxicity calculation are pointed and classification factors of radiological impact are calculated by making supplements of these problems. Also the improvement of classification factors for radionuclides derived is explained. The classification factor takes into account both of the exposure to and health effects of radionuclides, which makes supplement to existing Critical Volume (CV) approach. This calculation procedure makes it possible to consider the overall impact of each radionuclide and the pathways available. Also this calculation can be used in the case of non-uniform dose, and considers the gender and age specification of response to exposure. Even though some issues to be improved, this study has made important advances and could help the improvement of classification factor of radiological impact within the LCA framework and the promotion of the radiological risk assessment of nuclear fuel cycle. This study described once-through fuel cycle of nuclear energy system, constructed the environmental data set associated with the emissions and radionuclides to different environmental media and evaluated their environmental impacts using the LCA methodology. This is coincided with the current worldwide situation of the close relation between the environmental issues and energy policy. As a result, once-through fuel cycle turned out to cause the environmental impact of 4.32E-3 based on the un-dimensionally weighted value. The LCA methodology as an environmental management tool was suggested and its application to back-end of nuclear fuel cycles in a comparison of the once-through fuel cycle, the DUPIC cycle and the recycling with PUREX process was described. As a result, the recycling with PUREX process turned out to impose less significant environmental impact of 4.33E-4 rather than did the DUPIC of 1.19E-2 and once-through options of 4.32E-3. Also, the important environmental impacts in un-dimensionally weighted impact that could be associated with once-through fuel cycle currently implemented in Korea turned out to be resource depletion (4.12E-3), human toxicity through air (9.19E-5), ecotoxicity aquatic (4.8E-5), nutrification (3.43E-5) and human toxicity through water (1.29E-5). Radiological impact (1.06E-7) was less significant than other categories, even though a high relative significance factor was assigned. The significant environmental category was abiotic resource depletion caused by the utilization of uranium resources that was the major contributor of 95.4% to total environmental impacts, and the environmentally dominant stage was found to be mining/milling stage. Also 99% of radiological impact turned to be caused by mining/milling stage and power plant operation, and the most radiologically significant pathway was internal exposure, especially due to the inhalation of air. Nuclear and coal are major electricity generation sources in Korea, so it is necessary to take broader approach for comparative environmental assessment between two major energy resources before making long term energy planning. And it might be necessary to prove objectively the environmental predominance of nuclear energy over other energy sources considering various environmental categories. Therefore, emissions from coal-fired power plants are calculated using the emission factor provided by Ministry of Environment and the data associated with total raw material, energy, corresponding emission and wastes released during the normal operation of nuclear and coal fuel cycle facilities are cited from the annual report of KEPCO. Because all necessary data are not available in Korea, proper foreign references provide good supplements of Korean data. As a result, environmental categories such as resource depletion, global warming, human toxicity, eco-toxicity, acidification and nutrification are selected for comparison of nuclear and coal. Conclusively, electricity generation by nuclear turned out to cause less environmental impact than did coal by an order of magnitude. For the validation of results, environmental impacts calculated in other studies are compared to this study. Contribution of each nuclear fuel cycle to total environmental impact is compared with the results of United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) study. Also the benefits of recycling have proven with the study of BNFL and material flow used basically in the calculation of environmental impact is coincided with that of UNSCEAR study under the same condition. This study on application of the LCA methodology to alternative of nuclear power generation system gives some meaningful conclusions. This makes it possible to examine the environmental impact of chemical effluents in addition to the existing non-radiological impact assessment and to compare the significance of them with global warming, resource depletion, acidification and the radiological impact caused during normal operation of the nuclear facilities. Extensive database related with the nuclear and coal power generation system will be useful to the long-term energy planning and energy balance mix as source materials. This study has been still in progress and results are quite preliminary ones. Therefore, further study for the construction of more appropriate Korean data should be implemented. However, the results will establish and provide the extensive infrastructure of database related with power generation stages and be much helpful to make an improvement of ISO standardization of LCA methodology. Also decision on energy policy related with the environmental issues can be made for the long term electricity planning and the energy mix optimization considering the environmental aspect in Korea
[en] Highlights: • Seasonality patterns are a key aspect of the energy-water nexus. • Changes in streamflow seasonality slightly affect future revenue. • Changes in price seasonality may significantly affect the losses of revenue. • Price seasonality brings about more uncertainty on revenue than climate change. - Abstract: The energy-water nexus presents important implications at seasonal scale. For instance, electricity prices and streamflow have complex seasonal patterns and changes in both may adversely impact hydropower plant revenue. In order to quantify the effect of changes in price and water seasonality on future revenue distribution and its related uncertainty, we consider the case of a run-of-the-river plant. To this end, we integrate a hydrologic model, a hydropower model, two glacier inventories, six climate scenarios and five electricity price seasonal scenarios. Our results show that the impact of climate change on streamflow of the considered run-of-the-river plant will decrease the revenue by 20% in a business-as-usual price scenario. This decrease is mostly driven by a reduction of the annual streamflow due to glacier shrinkage rather than by the evolution of seasonality. From this perspective, the difference between the various climate scenarios is low. In contrast, change in electricity price seasonality induces a marked uncertainty in revenue. According to our scenarios, which assume no change in the mean annual electricity price, a change in price seasonality may indeed exacerbate or mitigate the impact of climate by 50 or 33% respectively, compared to the business-as-usual scenario. Our analysis highlights the need for considering intra-annual dynamics when investigating the energy-water nexus.
[en] Highlights: • A digital design framework consisting of three platforms and one center. • The functional features and application examples of the three design platforms. • The data scope and functional requirements of data management system. • The plant information model is proposed as the underlying database structure. • The application matrix of the data management system for engineering usage. - Abstract: Nuclear power design institutes such as SNERDI are shifting from conventional document-based and discipline-isolated design mode to data/model-based and full-discipline-collaborative digital design pattern. The digital design environment being developed in SNERDI is comprised of three design platforms and one data management system. The three platforms are the 3D plant layout platform, the 2D system design platform, and the calculation and analysis platform, whose main features are delineated. The data management system (DMS), as the kernel of the digital design environment, takes the role of collection, storage, configuration, control, display, and application of project data. The DMS combines the three design platforms, and makes design works data-driven and collaborative. The DMS is developed from scratch, whose data scope and functional requirements for nuclear power design can seldom be satisfied by commercial software, so were described in detail.
[en] The context in which this paper is set down concerns nuclear power, and this paper complements a number of more specialist treatments of aspects of the subject. Although it is, in consequence, perhaps to be expected that the discussion given would be specifically for a nuclear power plant the principles and methods of working involved apply equally to all kinds of power station projects though the actual fields of specialisation of team members, and the topics.of major discussion may vary from one project to another.
[en] The economic benefits of introducing nuclear systems on these vessels and platforms are significant. The advantage of a nuclear power system is that it is a high-density, large-capacity energy source. So, there is no need for frequent refueling like fossil fuels. In the case of floating nuclear power systems, it is possible to fundamentally solve the problem of securing the site as one of the biggest problems of the construction of a nuclear power plant, and has an advantage of supplying electric power to a remote island region from the mainland. In this paper, additional considerations have been considered when designing I&C systems for maritime applied nuclear systems based on the existing I&C system design considerations. According to the purpose of these nuclear system, the I&C system can have a variety of structures to provide various functions. For application environments that require multiple nuclear systems, high-level automation systems and I&C architectures such as integrated control and management systems may need to be considered.