New research from Iran shows that PV installations linked to battery storage may help prevent accidents and increase safety in nuclear power plants by acting as an emergency load. The scientists proposed a system design that considers both technical and economics factors.
A group of scientists from the Islamic Azad University in Iran has investigated how PV may be used as an emergency load to increase the safety of the Tehran Research Reactor (TRR) – a 5 MW pool-type light water research reactor operating at the Tehran Nuclear Research Center since 1967.
In the study “Design of emergency solar energy system adjacent the nuclear power plant to prevent nuclear accidents and increase safety,” published in Nuclear Analysis, the academics presented a design procedure based on the use of the PVSYST and RetScreen software.
“The main goal of this research is to use solar systems for providing emergency power to nuclear plants in case the power grid is down and other emergency systems such as diesel generators and batteries are not working,” they explained.
The researchers noted that the emergency load at the TRR facility is currently being provided by a 450 kW diesel generator located on the north side of the reactor building, and by a 50 kW diesel generator as a second backup source that could be used if the 450 kW system is damaged or under repair.
The research team proposed to install a 100 kW grid-connected PV system on a 627 m2 area. The system is planned to rely on 305 W polycrystalline modules and 5 inverters with an output of 20 kW each. Its expected that final output annual capacity will be 166.2 MWh. The scientists also assumed the PV array would be linked to a 400 kWh battery system that can provide an emergency load of 50 kW during 8 hours.
The solar plant is intended to back up the 50 kW generator to supply electricity to the nuclear plant's water pumps in case of emergency. “As the first priority, the plant charges the battery pack and discharges excess energy to the power grid,” the group explained. “The system is capable of both charging battery bank and transferring excess energy to the grid, simultaneously.”
According to the scientists, this project typology is technically and economically feasible if the solar plant is entitled to sell power to the grid under a feed-in tariff (FiT) scheme or a net metering regime, which would ensure significant profitability when the array is not used for emergency load.
Assuming the FiTs awarded by Iranian authorities, the scientists found the system's payback time is around 4.5 years.
“By evaluation of all schemes and economic data, it is concluded that construction of this plant leads to improving safety measures of nuclear reactors backed by solar power plants which is capable of generating energy for emergency loads for nuclear reactors,” they concluded. “This plant is a secure backup for nuclear reactors which prevents disasters like Fukushima Daiichi nuclear disaster.”