For more than 40 years, reactors located at Hanford produced plutonium for America’s defense program. The process of making plutonium is extremely “inefficient” in that a massive amount of liquid and solid waste is generated, while only a small amount of plutonium is produced. Additionally, all the facilities and structures that were associated with Hanford’s defense mission must also be deactivated, decommissioned, decontaminated, and demolished. That environmental cleanup project is the work that about 10,000 Hanford workers are involved in today.
Crews responsible for Site cleanup are dealing with several different kinds of waste in several different forms, with many of the wastes being potentially harmful to people and the environment. Precautions have been taken so that the waste does not contaminate the air, the ground, the water table underneath the ground, the Columbia River, the people who are doing the cleanup work, or the people and environment near the Hanford Site.
Solid waste can be everything from broken reactor equipment and tools to contaminated clothing that a worker wore during the plutonium production activities. The solid wastes were buried in the ground in pits or trenches. Some of the waste was placed in steel drums or wooden boxes before being buried while other waste was placed in the ground without a container to hold it. Depending on when the waste was buried, records about what was buried and where it was buried can be difficult.
Besides the millions of tons of solid waste, hundreds of billions of gallons of liquid waste were generated during the plutonium production days. These liquid wastes were disposed of by pouring them onto the ground or into trenches or holding ponds. Unintentional spills of liquids also took place. Liquid wastes generated during the process of extracting plutonium from the uranium fuel rods were put into underground storage tanks. Just like with the solid wastes, while some records accurately describe the kinds of liquid wastes that were generated and where they went, some of the spills and the volume of the spills went undocumented.
DOE removes equipment no longer needed from the AP Farm valve access pit. Crews will remove six waste-transfer piping
connectors from the pit before installing new equipment to support waste transfers and future AX-101 retrieval operations.
Reactor buildings, support facilities, and auxiliary structures needed during the plutonium production days must also be cleaned up. For many of these buildings, the work requires crews to come in with bulldozers and other heavy equipment to bring them down. As some of these structures are either contaminated or were built using materials like asbestos, crews must take precautions to avoid being contaminated themselves or to avoid releasing contamination into the ground, the air, or the groundwater.
DOE continues breaking up concrete and removing contaminated soil at several waste sites near the former K Area reactors on the Hanford Site. The area was home to underground fuel-oil storage tanks, pipelines and other infrastructure that supported the reactors during Hanford Site operations. The project is part of ongoing efforts to reduce risk to the nearby Columbia River. Contaminated soil and other debris are disposed of at the Environmental Restoration Disposal Facility, Hanford’s on-site engineered landfill.
During cleanup operations, where the waste will end up after it is removed from the ground is based upon waste characteristics. A majority of the solid wastes, contaminated soil, and building debris will be taken to the Environmental Restoration Disposal Facility (ERDF) located on the Hanford Site. This facility is regulated by the United States Environmental Protection Agency and is basically a huge landfill. ERDF accepts waste in disposal cells eight of which are 500 feet wide, 1,000 feet long and 70 feet deep and two of which are "super cells" that are twice as large. 2.8 million tons of waste can be disposed of in a cell at ERDF, and once each cell is filled up, the waste is covered with clean dirt and a soil fixative to ensure it will safely and permanently remain in the landfill.
Aerial image of the Environmental Restoration Disposal Facility
Some of the more hazardous chemical or radioactive solid wastes are not taken to ERDF. For example, the fuel rods that came out of the reactors but never had their plutonium extracted are stored in a facility called the Canister Storage Building at Hanford. Ultimately, these fuel rods will be sent for permanent burial at a national repository designed to accept these kinds of materials.
Solid transuranic waste is the debris that is contaminated with plutonium or other materials that may remain radioactive for hundreds of thousands of years. This waste, referred to as TRU waste, is securely packaged and shipped to the Waste Isolation Pilot Plant in New Mexico where it will be permanently and safely buried.
Of the liquid wastes generated at Hanford, much of the waste that is currently stored in the underground tanks on the Site will ultimately be transformed into a stable, glass product in a process called vitrification. In order to vitrify the waste, it is mixed with glass-forming materials and then introduced to high heat so that the waste bonds with the glass.
A Vit Plant crew added the first frit, or glass beads, to the melter inside the Low-Activity Waste Facility. Each bag of frit, seen here,
weighs 300 pounds. The team will add frit in regular intervals until about 40,000 pounds have been added and the molten pool
is about 31 inches deep. The Project recently completed heating the melter to its operating temperature of 2,100 degrees Fahrenheit.
In December 2023, the Waste Treatment and Immobilization Plant reached another historic milestone as teams successfully poured, filled, and transferred the first container of clean glass in the plant’s Low-Activity Waste (LAW) Facility. The first molten pool of glass was created during the commissioning process by heating up batches of glass beads, called frit, into the first of two state-of-the-art melters. The melters will transform Hanford’s low-activity radioactive and chemical tank waste into a vitrified glass form safe for disposal.
Once the vitrification process has taken place, the molten, glass-like material is poured into cylinders where it will cool and become solid. Ultimately, cylinders containing the most hazardous vitrified waste will be taken to a national repository for permanent burial. The cylinders with less hazardous waste are candidates for disposal in the Integrated Disposal Facility (IDF) located on the Hanford Site.
The liquid waste that had been poured onto the ground or held in ponds or trenches has long since evaporated or soaked into the soil on the Site. In doing so, the waste did contaminate some of the soil and is thought to have also created underground “plumes” of contaminants. A “plume” is kind of like an underground river where contaminants join with water that exists beneath the surface of the Earth. Many of these plumes move in varying speeds and move toward the Columbia River. Hanford employees are actively involved in projects designed to prevent any more of the contamination from reaching the river. Several different strategies are being used in that effort.
One strategy is simply to block the groundwater contamination from getting to the Columbia River. Various kinds of barriers are placed in the ground that allow the clean groundwater to move through, while chemically altering any harmful contamination into a non-toxic form as it passes through. Another strategy is called “pump and treat.”
The Hanford Site's 200 West Pump and Treat Facility
Through this process, contaminated groundwater is pumped out of the ground and treated with chemicals. These chemicals change the chemical makeup of the contaminants, rendering them harmless to the environment. Once the treatment of the groundwater is complete, the cleansed water is pumped back into the ground. Yet another strategy in dealing with groundwater contamination is called “biostimulation.” This is a new technology where crews pump materials like molasses and vegetable oil into the ground where tiny microorganisms in the soil eat the molasses and vegetable oil. The microorganisms then reproduce, and in doing so, they alter the chemistry of the groundwater and render the contaminants harmless to the environment. The process also prevents the contamination from moving any closer to the river.
Learn more by reading the current Hanford Site Fact Sheets.