Nuclear accidents are not far behind. Images of funnel-shaped nuclear reactors immediately call to mind places like Chernobyl, Three Mile Island, or Fukushima–all of which have become bywords for nuclear power’s lethality and unpredictability. And yet, when it comes to nuclear transportation in the United States, such fears are largely unfounded–thanks to stringent regulation and specialist transporters.
The transportation of nuclear, radioactive material is incredibly complex, and is governed by the Nuclear Regulatory Committee, which is also tasked with all matters relating to nuclear energy, ranging from nuclear reactors to the disposal of nuclear waste. The NRC is the United States’ nuclear watchdog, and it governs all aspects of nuclear energy with a cautious eye.
With that in mind, the NRC lays out three main goals for nuclear transportation :
- Contain the material. Any and all transport and containers must prevent leakages, spills, or seepage into the nearby environment, which has predictable consequences–ranging from soil pollution to groundwater contamination.
- Prevent unusual incidents, primarily criticality. Criticality is when nuclear materials reach critical mass, which can then result in nuclear fission. Essentially, nuclear materials must be rendered safe and transported without any threat of cross-contamination, which may lead to chain reactions, and therefore, nuclear fission.
- Shield any external radiation emitted by the nuclear material. As nuclear transport may cover a wide distance, it is imperative that the surrounding environment be safe from any emissions, including gamma rays and x-rays.
While nuclear waste comes in many forms, including spent fuel rods (solid waste), depleted uranium, and contaminated water (used as coolant in nuclear reactors), the NRC will assign an “A” value to each material, measured in curies, which determines its radioactivity value. It should be noted that “A” values vary based on whether the substance is in special form (encapsulated irradiated steel) or regular form (liquids or powders). Bear in mind that “A” values cannot exceed 1,000 curies.
Based on each material’s radioactivity and “A” value, there are primarily two types of containers that the NRC recognizes; fissile materials, or those capable of setting off chain reactions, are subject to additional regulations.
- Type A: Containers of this type are designed only to survive normal, everyday handling. While transport companies do need to have documentation on hand detailing the effectiveness of the design of Type A containers, they are primarily designed for everyday use and lower level materials with correspondingly lower curie values. Type A containers range from steel drums to wooden and cardboard boxes.
- Type B: Containers of this type are much stronger, reinforced, and tested to higher, considerably more rigorous standards. These containers almost always include some type of insulation shielding the inside material, and are generally double walled. Type B containers range from reinforced, double-walled steel drums that encapsulate tiny inner flasks of radioactive material to massive, concrete containers that can withstand impacts from runaway trains, speeding cars, or the derailment (or overturning) of the transporting vehicle. Often, Type B containers are tested by a variety of independent bodies, including the NRC and the prestigious Sandia National Laboratory, best known for their pioneering work on nuclear devices and weapons. Testing requirements for container durability include, but are not limited to:
- A 30-foot fall onto concrete surfaces;
- Puncture tests involving an approximate 3-foot fall onto a steel rod 6 inches thick;
- Immersion in depths of 3-600 feet of water for specified amounts of time.
Transport regulations are also quite stringent for higher-level nuclear materials. For instance, radioactive cargoes must:
- Have their routes filed in advance with the NRC and local and federal authorities (such as the Department of Transportation);
- Notify all relevant state, local, and federal authorities and law enforcement agencies;
- Adhere to a strict transport plan which transports may not deviate from;
- Be provided with armed escorts in populated areas;
- Be equipped with location tracking and multiple communication redundancies.
Indeed, much of this stringent legislation has paid off. As the NRC notes, only 1% of all Type A containers have failed, of which 39% have released their contents; of Type B containers, there has only been one failure, involving material for industrial radiography and imaging.