Thermo-Ecological Evaluation of Nuclear Power Plant within the Whole Life Cycle

Abstract

Polish energy sector is mainly based on coal combustion, which is responsible for increasing the CO2 emission. Simultaneously, European trends toward sustainability and global warming mitigation will lead to significant changes in the structure of electricity generation in Poland. Due to the domestic energy policy the increase of renewable resources utilisation, as well as installation of first nuclear power units (3x1.6 GWel), are planned in the perspective of the year 2030. The comparison of nuclear power plant with the existing coal ones requires the evaluation within the whole life cycle as well as the application of the common measure of the consumption of natural resources. Both requirements are fulfilled in the case of Thermo-Ecological Cost (TEC) analysis. TEC was introduced by Szargut and expresses the cumulative exergy consumption of non-renewable resources burdening the final consumed goods, e.g. electricity. Moreover, TEC takes into account the additional non-renewable exergy consumption required for mitigation of environmental losses caused by rejection of harmful waste products. In the paper, the TEC algorithm adopted for nuclear power plant is presented. In this case, the whole life cycle includes the following phases: 1) mining and milling, 2) conversion of fuel, 3) enrichment (diffusion or centrifuge), 4) fuel fabrication, 5) plant construction, 6) plant operations, 7) waste management, 8) plant decommissioning and 9) transport. The obtained results are compared with the average TEC index for the Polish energy mix. The direct exergy analysis shows that the direct exergetic efficiency of existing nuclear power unit is about 10% points lower than that of typical coal power unit. However, the TEC analysis proved that in the whole life cycle of the resource utilisation the exergetic efficiency is significantly lower in the case of the nuclear fuel cycle. The main cause of this imperfection appears in the stage of conversion, enrichment and nuclear fuel fabrication.

Influence of nuclear power unit on decreasing emissions of greenhouse gases

“…It can be made applying the so-called burn-up ratio coefficient, W F , expressed usually in GWd/tU and calculated as thermal output of reactor, Q th , related to mass of nuclear fuel delivered to the reactor m F [7]. Combining the energy efficiency (thermal efficiency) of the nuclear plant defined as a ratio of generated electricity to the rate of heat delivered to steam cycle η th = N el /Q th together with the burn-up ratio W F the energy and exergy efficiency of nuclear power plant can be calculated [1]. The results of calculations of exergy efficiency and system exergy efficiency for compared power technologies are summarised after [1] in Tab.…”

“…(2) and (3)) and results from Tab. 3 have been used for a comparative analysis of coal, natural gas and nuclear power plant analysed previously by means of TEC [1]. The obtained results are summarised in Tab.…”

“…Simultaneously, it is responsible for rejection of harmful wastes and greenhouse gasses (GHG) to the nature. It should be pointed out that from the point of view of the whole cycle of resources management from the cradle to grave (i.e., from raw material extraction, materials processing, manufacture, distribution, use, maintenance and disposal or recycling) the nuclear power chain is found as low efficient when comparing with other power technologies fed with nonrenewable primary energy [1,2]. However, on the other hand the reported accessible stock of resources of nuclear energy is much more abundant as that of fossil fuels.…”