Should a discussion about nuclear power go on long enough, it becomes inevitable that someone will scold that the only reason it has become unaffordable is the spread of safety regulations. The argument is seldom (if ever) substantiated – no specific regulation is ever identified as problematic, and there does not seem to be any consideration of the fact that we might have learned something in Fukushima, for example, that is deserving of regulation.
But there is now a paper that provides some empirical evidence that safety changes have contributed to the cost of building new nuclear reactors. The study also makes it clear that they are only one of several factors and only account for a third of the rising costs. The study also finds that, contrary to industry expectations, focusing on standardized designs doesn't really help, as costs continued to increase as more of a particular reactor design was built.
More of the same
The analysis carried out by a team of researchers at MIT is remarkably comprehensive. For many nuclear power plants, detailed construction records are available showing which building materials and workers were worked for and how much they each cost. There is also a detailed record of the safety regulations and when they were introduced in relation to the design. Finally, they also filed the patent applications for the companies that designed the reactors. The documents describe the motivations for design changes and the problems those changes were intended to resolve.
There are limits to how much even this level of detail can offer. For example, you cannot specify whether the costs for a certain number of workers in a certain building should be allocated to the implementation of safety regulations. In many cases, design changes have been made for a variety of reasons so that it is not just a safety / non-safety incident. However, the collection of sources allows them to make some very direct inferences about the sources of changing costs and to create very informed models from which the reasons for other costs can be inferred.
The researchers begin with a historical analysis of plant engineering in the United States. The basic numbers are bleak. The typical facility built after 1970 had cost overruns of 241 percent – and that doesn't take into account the cost of financing the construction delays.
Many in the nuclear industry view this, at least in part, as a failure to standardize designs. There is extensive literature on the expectation that building additional facilities based on a single design will mean lower costs due to the production of standardized parts, as well as management and worker experience with the construction process. This type of standardization is also a big part of the motivation for small, modular core designs that provide a reactor assembly line that then delivers finished products to installations.
However, many of the US nuclear power plants were built to the same concept, with obvious site-specific aspects such as different foundation requirements. Researchers track each of the designs used separately and calculate a "learning rate" – the drop in cost associated with each successful completion of a facility based on that design. If things went as expected, the learning rate should be positive, with each sequential plant costing less. Instead, it's -115 percent.
Where is the money going?
To find out what is causing these changes, one needs to delve into detailed accounting records of the construction of these nuclear power plants. Data on this was available for systems built after 1976. The researchers split the cost of 60 different aspects of the construction and found that almost all of them had increased, suggesting that there was probably no single, consistent cause for the price to increase. The biggest increases, however, were seen in what are known as indirect costs: engineering, purchasing, planning, planning, monitoring and other factors that are not directly related to the construction process of the facility.
The increased indirect costs affected almost all aspects of the plant construction. In terms of direct costs, the biggest contributors were simply the largest structures in the facility, such as the steam supply system, turbine generator, and security building.
Some of the changed costs are quite complicated. For example, many reactors have been redesigned to allow for more passive cooling, making the plant safer in the event of a hardware failure. This in turn required the separation of the reactor vessel from the walls of the security building. And that in turn enabled the use of lower quality steel (which lowered the price) but more of it (which more than made up for those savings). All of this changed the building process as well, although it's difficult to pinpoint exactly how this changed the amount of work.
To try to delve into the details, researchers tracked the progress of material delivery rates – how quickly material brought to the construction site was incorporated into a finished structure. While these rates fell slightly for the whole construction during the investigation period, they fell for nuclear projects. At the time of the accident on Three Mile Island, steel was already being used by around a third of the entire construction industry. Interviews with construction workers showed that they spent up to 75 percent of their time idling.
Since many of the researchers are in the nuclear engineering department at MIT, they can go through the cost changes and link them to specific motivations and examine those relationships by looking at patents and journal articles that describe the ideas that drive these changes.
Some of the driving factors are definitely regulatory. For example, following the accident on Three Mile Island, regulators called for "increased documentation of safety-compliant construction practices, prompting companies to develop quality assurance programs to manage the correct use and testing of safety-related equipment and nuclear construction materials." By implementing these programs and ensuring that the documentation adds additional costs to the projects.
But that wasn't the only cost by far. They cite a workers survey which found that about a quarter of unproductive work time came because workers waited for either tools or materials to become available. In many other cases, construction procedures were changed mid-construction, creating confusion and delays. Finally, there was the general decline in performance mentioned above. Overall, problems that decreased design efficiency contributed nearly 70 percent to the increased cost.
In contrast, R&D-related spending, which included both regulatory changes and things like identifying better materials or designs, made up the other third of the increases. Often times a single change has met multiple R&D goals, so allocating the full third to regulatory changes is likely to be an overestimation.
While safety regulations added to the cost, they were far from the main factor. Deciding whether it is worth the cost would require a detailed analysis of every regulatory change in the face of accidents like Three Mile Island and Fukushima.
For most of the cost explosion, the obvious question is whether we can do better. Here the researchers' answer is very much "maybe". You are looking at things like the ability to use a centralized facility to make high-performance concrete parts for the facility, as we did for projects like bridge building. However, this concrete is often more expensive than on-site cast materials, which means the higher efficiency of off-site production should more than make up for this difference. The performance of the material in the vicinity of a nuclear power plant has not been tested, so it is not clear whether this is a solution at all.
In the end, the conclusion is that there are no simple answers on how to build nuclear power plants more efficiently. Until then, it will continue to be undercut by both renewable energies and fossil fuels.
Joule, 2020. DOI: 10.1016 / j.joule.2020.10.001 (Via DOIs).