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The effect of cooling water temperature on the performance of a BWR nuclear power plant

Laskowski Rafał, Theimech Mohamad, Uzunow Nikołaj

Modern Engineering

2021

5--13

Although PWR reactors make up the large majority of the world's nuclear power plants, BWR reactors also have a share in this industry. It is difficult to find data on the performance of a BWR power plant in off-design and variable load conditions in the literature. Therefore, the paper presents how cooling water temperature affects the efficiency and power output of a BWR unit. The qualitative effect of changes and the trend related to the effect of cooling water temperature on the performance of the power plant are known, but the quantitative effect has to be determined for specific power units. Depending on the location of the nuclear power plant, various temperatures of cooling water for use in condensers and thus various operating conditions of the cooling system can be achieved. To analyze how cooling water temperature affects the performance of the power unit, a model of a BWR power plant was developed using the Ebsilon software. The model was based on data provided in [1] concerning LaSalle County Nuclear Generating Station. Calculations showed that within the examined range of cooling water temperatures at the condenser inlet between 10 and 28oC the gross power output of the unit decreases by 91.405 MW and the gross efficiency drops by 2.773 percentage points.

Modeling of liquid film flow in annuli

Anglart H.

Journal of Power Technologies

2014

Vol. 94, nr 5

8--15

One of the challenges in thermal-hydraulic analyses of BWRs is correct prediction of dryout occurrence in fuel assemblies. In practical applications the critical powers in fuel assemblies are found from correlations that are based on experimental data. The drawback of this approach is that correlations are valid only for these fuel assemblies on which the experiments have been conducted. Other restrictive factors are the limited ranges of experimental working conditions including pressure, mass flux and axial power distributions. To overcome the above-mentioned limitations, several different approaches have been proposed to predict the dryout occurrence. One of them is to employ a phenomenological model of annular flow, in which the mass transfer between the liquid film and the gas core is based on entrainment and deposition correlations. Most of these correlations are derived from water-air flows in vertical tubes and their applicability to other geometries in general, and rod-bundles in particular, should be analysed. This paper presents an analysis of the entrainment rate in vertical annuli. Using the standard approach to calculate the entrainment rate, one can demonstrate that the results deviate from measurements. It has been shown that modifying the entrainment correlation based on data obtained in the annulus geometry leads to an essential improvement in the predictive capability of the phenomenological model of annular two-phase flow.