Nuclear power plant? Or storage dump for hot radioactive waste?
Robert Alvarez 11 AUGUST 2016


In addition to generating electricity, US nuclear power plants are now major radioactive waste management operations, storing concentrations of radioactivity that dwarf those generated by the country's nuclear weapons program. Because the proposed Yucca Mountain nuclear waste repository remains in limbo, and other permanent storage plans are in their infancy, these wastes are likely to remain in interim storage at commercial reactor sites for the indefinite future. This reality raises one issue of particular concern—how to store the high-burnup nuclear fuel used by most US utilities. An Energy Department expert panel has raised questions that suggest neither government regulators nor the utilities operating commercial nuclear power plants understand the potential impact of used high-burnup fuel on storage and transport of used nuclear fuel, and, ultimately, on the cost of nuclear waste management.

Spent nuclear power fuel accumulated over the past 50 years is bound up in more than 241,000 long rectangular assemblies containing tens of millions of fuel rods. The rods, in turn, contain trillions of small, irradiated uranium pellets. After bombardment with neutrons in the reactor core, about 5 to 6 percent of the pellets are converted to a myriad of radioactive elements with half-lives ranging from seconds to millions of years. Standing within a meter of a typical spent nuclear fuel assembly guarantees a lethal radiation dose in minutes.

Heat from the radioactive decay in spent nuclear fuel is also a principal safety concern. Several hours after a full reactor core is offloaded, it can initially give off enough heat from radioactive decay to match the energy capacity of a steel mill furnace. This is hot enough to melt and ignite the fuel’s reactive zirconium cladding and destabilize a geological disposal site it is placed in. By 100 years, decay heat and radioactivity drop substantially but still remain dangerous. For these reasons, the US Government Accountability Office (GAO) informed the Congress in 2013 that spent nuclear fuel is “considered one of the most hazardous substances on Earth.”

US commercial nuclear power plants use uranium fuel that has had the percentage of its key fissionable isotope—uranium 235—increased, or enriched, from what is found in most natural uranium ore deposits. In the early decades of commercial operation, the level of enrichment allowed US nuclear power plants to operate for approximately 12 months between refueling. In recent years, however, US utilities have begun using what is called high-burnup fuel. This fuel generally contains a higher percentage of uranium 235, allowing reactor operators to effectively double the amount of time the fuel can be used, reducing the frequency of costly refueling outages. The switch to high-burnup fuel has been a major contributor to higher capacity factors and lower operating costs in the United States over the past couple of decades.

While this high-burnup trend may have improved the economics of nuclear power, the industry and its regulator, the Nuclear Regulatory Commission (NRC), have taken a questionable leap of faith that could, according to the Electric Power Research Institute, “result in severe economic penalties and in operational limitations to nuclear plant operators.” Evidence is mounting that spent high-burnup fuel poses little-studied challenges to the temporary used-fuel storage plans now in place and to any eventual arrangement for a long-term storage repository...