In 2018, nuclear energy generated 55% of United States’ and one third of the world’s carbon free electricity. Nuclear energy can be a key tool in current efforts to mitigate climate change before 2050. However, nuclear construction costs escalated dramatically in recent years: from $3,000/kW in the 1990’s to over $7,000 today, and this has severely limited its potential for impact. Nuclear plants are construction megaprojects that require thousands of workers and a decade of construction. The capital costs and construction timelines were double the original estimates for the last five nuclear plants completed or under construction in western nations. Moreover, the current nuclear technology can only provide heat at low temperatures (300°C), which limits its use as a decarbonization tool to the electricity grid. Heat for industrial processes accounts for 10% of carbon emissions. High temperature gas reactors (HTGRs) can meet this need with carbon free nuclear heat. Unfortunately, the estimated cost of advanced reactor alternatives such as HTGRs are even higher than current Light Water Reactors (LWRs). In this paper, we built a simple model to estimate the capital cost of existing nuclear plants and apply it to HTGR designs. We propose a structures-first design framework to minimize cost and apply it to the HTGR, resulting in a horizontal, integrated HTGR. The reactor core and steam generator are mounted on rails and in-line with one another. The rail-mounted horizontal orientation simplifies installation and eliminates the overhead crane. The proposed concept reduced the reactor building size by more than 50%/kW relative to other HTGR designs, putting the building power density on par with LWR designs but with the inherent safety and high temperature capability of an HTGR. Finally, we estimate a >30% cost reduction from the new design and the potential impact on carbon emissions.
Keywords HTGR, nuclear power plant economics, cost