By John C. Zink, Ph.D., P.E., Contributing Editor
Congress and the president have finally jumped through all the prescribed hoops to officially approve Yucca Mountain, Nev., as the country’s first permanent high-level nuclear waste repository. The state of Nevada continues to fight Yucca Mountain with all the legal and public relations power it can muster. Now the state is trying to stir up public concern about the transportation of nuclear waste to the repository.
When the Yucca Mountain decision came before Congress, Nevada was effectively isolated, with all but the most strident anti-nuclear politicians voting to send their state’s waste to the Nevada desert. Now, Nevadans are trying to overcome that isolation by alarming people in other states about nuclear waste shipments which may come through their area.
As often happens in the nuclear debate, the two sides agree on very little. For example, it should be easy to determine the expected number of shipments to the site: simply take the repository’s capacity and divide it by the average size of a shipment. The U.S. Department of Energy (DOE) projects a total of 4,300 waste shipments to Yucca Mountain over a 24-year period. DOE prefers that about 95 percent of the shipments be by rail, with each shipment carrying about 15 to 20 tons of spent fuel. Nevada claims the number will be more like 35,000 to 100,000 shipments. The state maintains that, since there is currently no rail service to Yucca Mountain, all shipments must be by truck, and each truck can carry only one to two tons of spent fuel. Thus, Nevada calculates the number of shipments to be up to 20 times larger. Nevada has attempted to gain allies by asserting that this large number of shipments will affect many other states. The state government has produced a report titled “Will Nuclear Waste Travel Through Your State?”
DOE has some control over the matter, however, because that agency will operate the repository when it begins accepting waste in 2010. DOE is considering building a long rail spur to the site or, alternatively, using “intermodal” transportation. This means that rail cars carrying spent fuel would be offloaded at some convenient point, and the final leg of the journey would be made by truck. While the second option could create a large number of truck shipments in the vicinity of the repository, those shipments would not cover great distances or go through other states.
DOE points out that, over the past 30 years, there have been more than 2,700 shipments of spent nuclear fuel in the U.S., with a total distance traveled of more than 1.6 million miles. In the last three years alone, the Waste Isolation Pilot Plant near Carlsbad, N.M., has received nearly 700 spent fuel shipments, covering a cumulative 1.5 million miles. DOE notes that, in no case, has there been a release of radioactive material which has harmed the public or the environment. DOE also points out that France and Britain, both smaller, more densely populated countries than the U.S., safely transport about 650 spent fuel shipments a year.
As part of its responsibility for oversight of Yucca Mountain, the Nuclear Regulatory Commission (NRC) has undertaken several transportation-related studies. For one study, NRC retained Sandia National Laboratory to update its 1987 assessment of the adequacy of spent fuel shipping casks. Sandia has concluded that it is most important to revisit the earlier studies involving fire-resistance testing, impact testing, and accident probabilities. Sandia will use the latest analytical techniques, such as computational fluid dynamics, as well as focused tests to verify the adequacy of current cask designs. Sandia should complete its re-evaluation of shipping cask performance by 2005.
NRC also reevaluated its 1977 risk assessment for the entire process of shipping spent fuel. This reevaluation, released in 2000 as NUREG/CR-6672, examined the total risk presented by both highway and rail shipments of spent fuel. The new study accounts for the expected lower radiation levels of the spent fuel, due to its longer time on-site, and more accurately portrays the actual transportation routes. It also uses more sophisticated computer models for predicting cask behavior under various accident scenarios. After considering the probability of accidents, their severity and their consequences, NRC concluded that the 1977 study was overly conservative. The updated study determined that radiation exposure risk resulting from highway accidents is nearly 1,000 times lower than previously thought, and the risk from railway accidents is more than 50 times lower than previously thought. Characteristically, just to be extra safe, the NRC has decided to continue to use the old, ultra-conservative numbers as its official assessment of the radiological impact of shipping spent fuel.
Like so many other issues raised by nuclear power’s foes, nuclear waste transportation is a red herring. Experience shows that it has been done safely in the past, and analysis shows that it will not create a significant public hazard in the future.