Used nuclear fuel will arrive at the HI-STORE CISF by rail in robust and safe transport casks using specialty-designed railcars. Three transportation casks designed by Holtec International and licensed by the U.S. Nuclear Regulatory Commissioning (NRC), HI-STAR 190, HI-STAR 100 and HI-STAR 100MB (HI-STAR is an acronym for Holtec International Storage Transportation and Repository) could be used to move used nuclear fuel from the reactor sites to the HI-STORE CISF. The HI-STORE CISF will provide the ability to readily extract the used fuel canisters and ship them to a permanent repository as soon as it is available.
U.S. Used Nuclear Fuel Transportation Experience is Impeccable
According to a U.S. Department of Energy (DOE) report prepared by the Oak Ridge National Laboratory and Argonne National Laboratory, more than 25,000 shipments of used nuclear fuel have been made worldwide to date, shipping more than 87,000 metric tons of fuel. Review of the data sources shows that all of these shipments were undertaken without any injury or loss of life.
In the U.S., except for a limited amount of transport, the majority of used nuclear fuel remains at the reactor sites. Nevertheless, more than 1,300 used fuel shipments have been completed safely over the past 35 years in the U.S., according to the NRC, with most shipments performed by rail. Thanks to the robust transportation cask designs and stringent safety measures adopted by the industry, every one of these used fuel shipments has been safely completed with no release of radioactivity or environmental damage.
Transportation of Used Nuclear Fuel is Highly-Regulated
Part of the reason for this impeccable record mentioned above is the fact that transportation of radioactive material, including used nuclear fuel, is strictly regulated by each country’s nuclear regulatory agencies. In the U.S., these regulators include the Nuclear Regulatory Commission (NRC) and the U.S. Department of Transportation (DOT). The NRC oversees the design, manufacture, use, and maintenance of casks for these radioactive shipments. The DOT coordinates with the NRC to set rules for the packaging of nuclear material, regulates carriers, and sets standards for routes. DOT also works with the NRC and affected States to regulate the transport operations while they occur.
Designs, Regulations and Safety Measures
Transportation casks for shipping used nuclear fuel are robustly designed to protect the public from releases of radioactive material in the unlikely event of an accident. The NRC regulates the design and construction of these casks by requiring that the candidate cask must demonstrate that it can survive four successive accident conditions involving free drop, puncture, fire and submersion in water events before it is considered fit for transportation. Casks, such as Holtec’s HI-STAR 190, HI-STAR 100 and HI-STAR 100MB are designed and fabricated with multiple layers of steel, lead and other materials to safely confine the fuel, shield workers and the public from radiation associated with the fuel. Inside the cask, the used nuclear fuel, in solid form, is confined inside a strength-welded canister, allowing no pathway for the radiological matter to escape to the environment. Hence multiple layers of protection stand between the cask’s contents and the environment. Fully loaded casks weigh 125 tons or more for rail shipments. Typically, for every ton of used fuel, a cask has about 4 tons of robust shielding material.
Dose from Transportation of Used Nuclear Fuel is Negligible
The NRC regulatory limit for dose rates around the cask is 10 mrem/hr at 2 meters from the vehicle. As a comparison, the dose from a single dental x-ray is about 4 mrem. That means that a person standing 2 m away from a vehicle with a transport cask, for 24 minutes (0.4 hours), would receive just about the same dose as from a single dental x-ray. However, that is not a realistic condition to consider for any member of the public. A member of the public would be further away from a transportation cask, and typically for a shorter period of time, hence the dose would be much lower. Rather than evaluating the dose to an individual member of the public, it is therefore more meaningful to evaluate the total collective dose to all members of the public near the transport path for a transportation cask. The NRC has performed and published such evaluations, for several transport routes across the United States, for both rail and truck transports. For rail transport, the collective dose is between 8 and 120 mrem, depending on the route. Note that this is the collective dose for the entire public along the route (in some cases more than 1 million people), including residents along the route, occupants of vehicles sharing the transport route, crews and escorts, and anyone near a stop, not for a single person. The maximum value for a single person would be substantially below the value of 4 mrem stated above for the dental x-ray. Another good comparison can be made with the background radiation that every person receives. The dose from the transport is only a very small fraction, less than 1/1000, of the typical background radiation that people would receive at the same time making the dose from transportation of used nuclear fuel truly negligible.