Why are nuclear plants so expensive? Safety’s only part of the story

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A picture of two cooling towers for the power plant.

In the event that any discussion about nuclear energy continues long enough, it becomes inevitable that someone will say that the only reason it is unaffordable is the proliferation of safety regulations. This argument is rarely (if any) materialized – no specific regulation has been identified as a problem, and it seems that there is no consideration of the fact that we may have learned something in, say, Fukushima That may be worth addressing by regulations.

But now there is a research paper that provides some experimental evidence that safety changes have contributed to the cost of building new nuclear reactors. But the study also shows that it is only one of a number of factors, and it accounts for only a third of extreme costs. The study also found that, contrary to what those in the industry expect, focusing on standardized designs doesn’t really help matters, as costs have continued to grow as more and more of a particular reactor design is built.

More of the same

The analysis, conducted by a team of researchers at the Massachusetts Institute of Technology, is remarkably comprehensive. For many nuclear plants, they have detailed building records, broken down into different building materials and labor, and how much each will cost. There is also a detailed record of the safety regulations and when they were put in place in relation to construction. Finally, they also filed for patent applications from the companies that designed the reactors. The documents describe the drivers for the design changes and the problems that these changes aim to solve.

There are limits to how much this level of detail can provide. You cannot specify, for example, whether the cost of a certain number of workers in a particular building must be allocated to implement safety regulations. And in many cases, design changes have been made for multiple reasons, so there is simply no safety / insecurity breakdown. However, the range of sources they have allows them to come to some very direct conclusions about the sources of variable costs and build highly informed models that can infer causes of other costs.

The researchers begin with a historical analysis of factory building in the United States. The core numbers are bleak. A typical plant built after 1970 had a cost to run over 241 percent – that doesn’t take into account the costs of financing construction delays.

Many in the nuclear industry argue that this, at least in part, has failed to standardize designs. There is extensive literature on the expectation that building additional plants based on a single design will mean lower costs due to production of standard parts, as well as the experience of management and workers in the construction process. This kind of standardization is also a big part of the drive behind small modular nuclear designs, which envision a reactor assembly line that then ships the finished products to the facilities.

But many US nuclear plants are actually built around the same design, with clear site-specific aspects such as different foundation needs. Researchers track each design used separately, and calculate a “learning rate” – the cost reduction associated with each successful completion of a plant based on that design. If all goes as expected, the learning rate should be positive, with a lower cost per serial plant. Instead, it is -115 percent.

Where does this money go?

Knowing the reason for these changes included diving into detailed accounting records about the construction of these nuclear plants. Data on this was available for factories built after 1976. Researchers split the cost of 60 different aspects of construction and found that nearly all of them rose, indicating that there is unlikely to be one single reason for the price. Increase. But the largest increases occurred in what they called indirect costs: engineering, procurement, planning, scheduling, supervision, and other factors not directly related to the process of building the plant.

The increased indirect costs affected nearly every aspect of plant construction. In terms of direct costs, the largest contributors were simply the largest structures in the plant, such as the steam supply system, the turbine generator, and the containment building.

Some of the variable costs are rather complicated. For example, many reactors have switched to a design that allows more passive cooling, making the plant safer in the event of hardware failure. This, in turn, requires separating the reactor vessel from the walls of the containment building. This, in turn, allowed the use of lower quality steel (which lowered the price), but more of it (which compensated for these savings). All this also changed the construction process, although it is difficult to determine exactly how this changed the amount of labor required.

To try to dive into detail, the researchers tracked the progress in material deployment rates – how quickly the material brought to the site was incorporated into a completed structure. While these rates decreased slightly for construction as a whole during the study period, they decreased for nuclear projects. At the time of the Three Mile Island accident, steel was sawn at about a third of the construction industry overall rate. Interviews with construction workers indicated that they were spending up to 75 percent of their time idle.


Because many researchers work in the MIT nuclear engineering department, they are able to move forward and link cost changes to specific drivers and verify these links by looking at patents and journal papers describing the ideas driving these changes.

Some of the driving factors are definitely regulatory. After the Three Mile Island accident, for example, regulators “required increased documentation of safety-compliant construction practices, which led companies to develop quality assurance programs to manage the correct use and testing of safety-related equipment and nuclear building materials.” Put these programs in place and ensure documentation has added costs to projects.

But these weren’t the only costs. They cite a worker opinion survey that indicated that about a quarter of unproductive work time came because workers were waiting for either tools or materials to become available. In many other cases, construction procedures were changed in the middle of construction, resulting in confusion and delays. Finally, there was an overall decline in the performance indicated above. Finally, problems that reduced building efficiency by nearly 70 percent contributed to the increase in costs.

In contrast, expenditures on research and development, which included both regulatory changes and things like identifying better materials or designs, made up the other third of the increases. Often times, one change achieved many R&D goals, so allocating a full third to organizational changes would be an overestimate.

So, while safety regulations added to costs, they were far from the main factor. Determining whether these costs are worthwhile will require a detailed analysis of each organizational change in light of incidents such as Three Mile Island and Fukushima.

For the majority of the cost explosion, the obvious question is whether we can do anything better. Here, the researchers’ answer is “maybe.” They’re thinking of things like the possibility of using a central facility to produce high-performance concrete parts for the plant, and we’ve moved on to doing projects like building bridges. But this concrete is often more expensive than the material poured on site, which means that the higher efficiency of off-site production should compensate for this difference. The materials’ performance has not been tested in a nuclear plant environment, so it is not clear if this is a solution or not.

In the end, the bottom line is that there are no easy answers how to make building a nuclear plant more efficient. Until that happens, both renewables and fossil fuels will continue to be severely undermined.

JulesDOI: 10.1016 / j.joule.2020.10.001 (About DOIs).

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