Sat. Oct 1st, 2022
Image of two cooling towers of a power plant.

If the discussion about nuclear power goes on long enough, it is inevitable that someone will rant that the only reason it has become unaffordable is a proliferation of safety regulations. The argument is rarely (if ever) elaborated – no specific regulation is ever identified as problematic, and no attention seems to be paid to the fact that we may have learned something in, say, Fukushima that would be worth regulating via regulation. to grab.

But a paper has now emerged that provides empirical evidence that changes in safety have contributed to the cost of building new nuclear reactors. But the study also makes clear that they are just one of a number of factors, accounting for only a third of rising costs. The research also found that, contrary to industry expectations, focusing on standardized designs didn’t really help, as costs continued to rise as more of a particular reactor design was built.

More of the same

The analysis, conducted by a team of researchers at MIT, is remarkably comprehensive. For many nuclear power plants, they have detailed construction reports, broken down by the various construction materials and labor, and how much they all cost. There is also a detailed overview of safety regulations and when they are in place with regard to construction. Finally, they also filed the patent applications filed by the companies that designed the reactors. The documents describe the rationale for design changes and the problems these changes were intended to solve.

There are limits to how much even this level of detail can provide. For example, you cannot determine whether the costs of a certain number of employees in a certain building should be allocated to the execution of safety regulations. And in many cases, design changes have been made for multiple reasons, so it’s not just a safety/non-safety failure. Still, the collection of sources they have allows them to draw some very direct conclusions about the sources of changing costs and to build informed models that can infer the reasons for different costs.

The researchers start with a historical analysis of factory construction in the US. The base numbers are bleak. The typical factory built after 1970 had a cost overrun of 241 percent — and that’s not taking into account the financing costs of the construction delays.

Many in the nuclear industry view this as, at least in part, a failure to standardize designs. There is an extensive literature on the expectation that building additional factories from one design will reduce costs through the production of standardized parts, as well as management and employee experience with the construction process. That kind of standardization is also a big part of the motivation behind small, modular nuclear designs, which envision a reactor assembly line that then ships finished products to installations.

But many of America’s nuclear power plants were in fact built around the same design, with obvious site-specific aspects such as different foundation needs. The researchers track each of the designs used individually and calculate a ‘learning rate’: the cost reduction associated with each successful completion of a plant based on that design. If everything went as expected, the learning rate should be positive, with each successive installation costing less. Instead, it’s -115 percent.

Where does that money go?

To find out what caused those changes was to dive into detailed accounting records of the construction of these nuclear power plants; data on this was available for plants built after 1976. The researchers calculated costs for 60 different aspects of the construction and found that nearly all of them went up, suggesting there probably wasn’t a single, unifying cause for the price to increase. But the biggest increases were in what they called indirect costs: engineering, procurement, scheduling, scheduling, supervision, and other factors not directly related to the process of building the plant.

Increased indirect costs impacted 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, turbine generator, and containment building.

Some of the modified charges are quite complicated. For example, many reactors switched to a design that allowed for more passive cooling, which would make the plant safer in the event of hardware failure. That, in turn, required separating the reactor vessel from the containment building walls. And that, in turn, allowed for the use of lower quality steel (which lowered the price), but more of it (which more than offset those savings). All of this also changed the construction process, although it is difficult to determine exactly how this changed the amount of labor required.

To try and dig into the details, the researchers tracked the progress of material deployment: how quickly material brought to the site was eventually incorporated into a completed structure. While those rates for construction as a whole fell slightly during the study period, they fell for nuclear projects. At the time of the accident on Three Mile Island, steel was being used at about a third of the pace of the construction industry in general. Interviews with construction workers revealed that they were inactive for up to 75 percent of their time.


Because many of the researchers work in MIT’s Department of Nuclear Engineering, they are able to go through the cost changes and link them to specific motivations and check these connections by looking at patents and journal articles describing the ideas driving these changes. underlie.

Some of the driving factors are certainly regulatory. After the accident on Three Mile Island, for example, regulators demanded “more documentation of safety-compliant construction practices, prompting companies to develop quality assurance programs to manage the proper use and testing of safety-related equipment and nuclear building materials.” By setting up those programs and making sure that the documentation provided both the cost of the projects.

But those were far from the only costs. They cite a workers’ survey which indicated that about a quarter of unproductive working time was because workers waited for tools or materials to become available. In many other cases, construction procedures were changed midway through construction, leading to confusion and delays. Finally, there was the general performance drop mentioned above. All in all, issues that reduced construction efficiency contributed nearly 70 percent to the increased cost.

By contrast, R&D-related spending, which includes both regulatory changes and things like the identification of better materials or designs, accounted for the other third of the increases. Often a single change met multiple R&D goals, so attributing the full third to regulatory changes is likely an overestimation.

So while safety regulations increased costs, they were far from the main factor. And deciding whether it was worth it would require a detailed analysis of any regulatory change in the face of accidents such as Three Mile Island and Fukushima.

As for the bulk of the cost explosion, the obvious question is whether we can do better. Here, the researchers’ answer is very much a “maybe”. They’re thinking of things like the ability to use a central facility to produce high-quality concrete parts for the factory, as we’ve moved into projects like bridge building. But this concrete is often more expensive than on-site cast materials, meaning the higher efficiency of off-site production should more than make up for that difference. The performance of the material in the environment of a nuclear power plant has not been tested, so it is not clear whether it is a solution.

Ultimately, the conclusion is that there are no easy answers to make nuclear power plant construction more efficient. And until there are, it will continue to be severely undercut by both renewables and fossil fuels.

Joules2020. DOI: 10.116/j.joule.2020.10.001 (About DOIs).

By akfire1

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