‘Nuclear waste’ refers to any material leftover from processes within the nuclear fuel cycle and from the production and maintenance of nuclear weapons. This includes wastes from the initial uranium extraction and processing, depleted uranium from enrichment, and spent fuel after the generation of nuclear energy. Nuclear waste includes byproducts from these processes that are not usable to generate further energy and may contain plutonium if reprocessing has not occurred. Nuclear waste is radioactive and can be hazardous to humans and the environment if not handled properly.
Nuclear waste is heavily regulated as a hazardous material. In the United States, nuclear waste is regulated by the Nuclear Regulatory Commission. Internationally, nuclear waste management is addressed through the International Atomic Energy Agency’s Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management, along with regulations set by individual countries.
Nuclear waste includes depleted uranium, plutonium if reprocessing has not occurred, radium, and other actinides such as neptunium and americium, as well as other radioactive elements that emit alpha, beta, gamma, and neutron radiation. Any objects exposed to radiation throughout the nuclear fuel cycle are also considered nuclear waste. Refer back to early Nuclear 101 segments for a discussion of radiation (Types of Radiation Part 1 and Part 2) and radioactive half-life. Nuclear waste storage and disposal practices must be able to contain all forms of radiation until complete radioactive decay has been obtained and the material is no longer hazardous.
There are three types of nuclear waste: high level, intermediate level, and low level wastes. Most often the phrase ‘nuclear waste’ refers to the highly radioactive high level waste.
- High level wastes are byproducts from the nuclear fuel cycle. Although only making up about 3% of all nuclear waste, high level waste products contain 95% of all radioactive nuclear waste.
- Intermediate level wastes make up about 7% of all nuclear waste and 4% of all radioactive nuclear waste. Intermediate level wastes include objects such as filters or components used within reactors or other processes that have come into direct contact with radioactive materials.
- Low level wastes make up about 90% of all nuclear waste and only about 1% of all radioactive nuclear waste. Low level waste is comprised of lightly-contaminated items such as tools or work clothing worn in radioactive areas.
Low Level Waste
Some low level waste can be compacted and incinerated. Other low level nuclear waste is packaged into containers lined with lead, steel, or concrete to offer radiation shielding that is appropriate for the level of hazard the waste presents. Low level waste can be stored in secured buildings or other secluded sites until moved to a final disposal site.
This photo shows an example of a low level waste storage pit at the Nevada National Security Site.
Intermediate level waste can often be disposed of in the same manner as low level waste. Some intermediate level waste, such as that which has been exposed to more radiation for a longer period of time, may require additional radiation shielding and would be treated more as a high level waste product.
High Level Waste
High level nuclear waste can be stored temporarily in two ways: wet and dry storage.
Wet storage involves the immersion of storage containers under more than 20 feet of water inside a concrete and steel-lined pool. Because hydrogen has the ability to break chemical bonds of radioactive particles, water offers a natural barrier against radiation. These containers are often kept within the pool for about 5 years until, due to space limitations, moved into dry cask storage.
Dry cask storage typically involves an airtight metal cylinder containing the waste enclosed in a concrete outer shell to provide additional radiation shielding. Dry casks are generally stored above ground in a secure location.
The Ongoing Debate Over the Safety of Nuclear Waste Storage Facilities
The Nuclear Regulatory Commission requires that wet and dry storage facilities take safety and security seriously. Security features include intrusion detection, alarms, and response to intruders when necessary. Safety requirements include protection against seismic events, tornadoes, and flooding. Regardless of the requirements, critics have been vocal regarding safety and security vulnerabilities that still persist. For instance, the Waste Isolation Pilot Plant in New Mexico, a facility that houses nuclear waste from the country's nuclear weapons industry, released high levels of radiation exposing at least 13 workers in February 2014. This was only two weeks following an incident at the same facility in which a truck carrying radioactive material caught fire causing the facility to shut down temporarily.
All nuclear waste storage options are intended to be temporary. It may take 100,000 years of radioactive decay for high level nuclear waste to become inert. A permanent disposal option is needed. Nuclear 101: Nuclear Waste Part 2 will discuss nuclear waste disposal and current initiatives for permanent waste repositories.
American Physical Society
International Atomic Energy Agency
Nevada Test Site Guide
Nuclear Energy Agency
Nuclear Energy Institute
Nuclear Regulatory Commission: Regulation
Nuclear Regulatory Commission: Radioactive Waste: Production, Storage, Disposal
Nuclear Regulatory Commission: Dry Cask Storage
Nuclear Regulatory Commission: Spent Fuel FAQ
World Nuclear Association: What are nuclear wastes?
World Nuclear Association: Waste Management