SPECIAL REPORT | NUCLEAR-RENEWABLES TIE IN
Above: Solar can supply energy to the grid but also reliable back-up power for a reactors emergency systems and coolant pumps
operating separately. But in a recent paper published in
Nuclear Analysis the authors (M. Chabook and S. Tashakor from Iran’s Islamic Azad University) investigate whether onsite PV and a battery could be used to increase safety at a nuclear plant. In their paper, titled “Design of emergency solar energy
system adjacent the nuclear power plant to prevent nuclear accidents and increase safety”, they said: “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 modelled a relatively small-scale installation at
the Tehran research reactor, a 5 MW pool-type light water research reactor that has been operating at the Tehran Nuclear Research Center since 1967. Emergency power at the Tehran research reactor for pumps, motors, light and all electrical equipment and labs is provided by a 450 kW diesel generator on the north side of the reactor building. This unit is backed up by a separate 62.5 kVA/50 kW diesel generator.
The authors say PV and a battery could back up the 50
kW generator (in case it failed or fuel was unavailable) and supply electricity to water pumps until the reactor’s other power systems are recovered. Iran is an ideal location for such an installation. It has high solar irradiation, with typically 300 sunny days per year. In many areas in Iran PV receives 5.4–5.5 kWh/m2 m2
, far above the level (3.5 kWh/ ) where international standards typically consider
irradiation is sufficient to allow for economic use of solar PV. The study used standard software (PVsyst) designed for analysis and simulation of photovoltaic installations, which can simulate the performance of solar in each country, city and zone. They used a second standard software tool (RETScreen Clean Energy Management Software) developed by the Government of Canada that allows for assessment and optimisation of the technical and financial viability of renewable energy, energy efficiency and cogeneration projects. The research team considered the option of installing a 100 kW grid-connected PV system, which would require
18 | September 2024 |
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an area of 627 m2
of area, linked to a 400 kWh battery. The
battery system can provide the necessary emergency power of 50 kW for eight hours. The model solar plant is intended to back up the 50 kW generator, which supplies electricity to the nuclear plant’s water pumps in case of emergency but the authors decided to model a larger array so that it also had more opportunity to export power to the grid (it also used novel inverters that allow for connection both to the grid and to battery packs). “As the first priority, the plant charges the battery pack and discharges excess energy to the power grid,” the authors explained, adding: “The system is capable of both charging battery bank and transferring excess energy to the grid, simultaneously.” The paper concludes that the 100 kW solar power
plant, connected to the grid, leads to improved back up capabilities at the Tehran research reactor. The system as designed could also generate revenue by selling surplus electricity to the electricity grid as when backup power is not required any excess generated energy is transferred to the power grid, with an associated income for the operator. In an economic evaluation, the authors said 16,500 million Rials (US$390,000) was required for construction of the plant and annual maintenance cost would be 210 million Rials (US$5000). Economic evaluations suggested that the project could pay off its capital investment after 4.5 years, as long as exported power was able to access Iran’s solar feed-in tariff. These types of exploration of the opportunities of other
forms of generation on nuclear sites hints at potential new revenue lines for nuclear operators elsewhere. Such revenue lines may be public-facing: EV chargers like those linked to PV – as well as nuclear – at Dukovany offer carbon-free power direct to EV drivers. But operators may also offer more specialist services to the power industry: together with the energy (and inertia) traditionally provided by nuclear, products like flexibility and fast frequency response are increasingly valued in the modern electricity market. Alongside the bulk of a nuclear station, arrays of
batteries may become increasingly common – and PV may be everywhere. ■
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