Efficiency and economic assessment of combining nuclear power plants with multifunctional heat accumulation systems

The current problem related to operation of nuclear power plants within power grids is caused by the base-load level achieving its maximum. The growing share of NPPs in the power systems requires their involvement in the regulation of load curve irregularities. At the same time, operation of an NPP with the maximum installed capacity utilization factor is economically and technically scientifically grounded. According to the scheme of combining an NPP with a heat accumulator, during the nighttime decrease in electricity consumption, the main steam from the NPP steam generator flows for heating the heat storage material. During the peak-load hours, the accumulated energy can be used to increase the capacity of the NPP power unit due to additional heating of the feed water. This research is based on the standard methods of thermodynamic and technoeconomic analysis. The conducted computational experiments include computer simulation by the finite element method. Investigation into economic efficiency of the technology included analysis of a wide range of electricity rate structures with particular account for a possibility to refuse from high-priced PRHR heat exchangers due to additional emergency backup of NPP auxiliaries. The calculations show that the accrued net present value of the proposed system will amount $ 4.4-12.5 million over the 25-year accounting period under the accepted tariffs for the supplied peak and off-peak electricity, in conditions of combining the system with NPP power unit containing a VVER-1000 reactor.