When the decision to stop producing plutonium at Hanford was made in the late 1980’s, there were more than 100,000 uranium fuel rods and rod fragments that had been irradiated in Hanford’s N Reactor, but would not be processed any further to extract plutonium. Subsequently, these fuel rods needed to be stored until the decision was made about where these rods would ultimately end up.
It was determined that these fuel rods would be placed temporarily in two, water-filled storage areas adjacent to the K-East and K-West Reactors. Called the KE- and KW-Basins, each of these basins contained about 1,000,000 gallons of water, and they were located about 400 yards from the Columbia River.
The K-Basins were built in the 1950’s, and at that time, they were built for a 20-year mission. The basins were already beyond their anticipated service lives when these fuel assemblies were placed in them, and the basins were not built to store spent nuclear fuel for decades as they had to do. By the 1990’s, it was discovered that the KE Basin had continued to leak contaminated water into the ground. Additionally, the fuel rods in both basins had started to deteriorate, resulting in the formation of a material called “sludge.” This sludge consisted of tiny fuel corrosion particles, fuel rod fragments, other metal fragments, wind-blown sand, and other materials. As long as the water wasn’t disturbed, crews could see the sludge which sat in a gray layer on top of the other wastes within the basins. However, whenever the water was disturbed, the sludge would become mobile, and make the water so cloudy that no one could see into it.
With the fuel rods continuing to deteriorate, and the discovery of additional contaminated water leaking into the ground so close to the Columbia River, removing the water and materials contained in the K-Basins began in 1994. By 2004, crews had completed the removal of 2,100 metric tons of irradiated fuel rods from the basins and had safely moved the material into Hanford’s Canister Storage Building. The fuel rods will remain in the Canister Storage Building until such time as a permanent, national repository for spent fuel is built.
The removal of the fuel rods allowed crews to begin the tedious process of vacuuming out the sludge, sediment and debris that had accumulated on the floors of the basins. The crews started with KE Basin and transferred the sludge to KW Basin so all the sludge could be stored there until ready for treatment. Ultimately, some 47 cubic yards of radioactive sludge were successfully containerized for safe storage in the KW Basin by the end of 2007.
With the removal of the sludge from the KE Basin, Hanford workers were able to drain its water and transport the liquid to a facility for treatment and start demolition of the structure. Crews at the KE Basin have completed demolition of the entire structure of the KE Basin. The adjacent reactor will now be placed into Interim Safe Storage (ISS).
In addition to work on the K Basins themselves, demolition of ancillary facilities and remediation of waste sites associated with the 100 K area has begun. Demolition of the 183.KW and 183.KE sedimentation basins, which were used to store water needed to run the KW and KE reactors respectively, has been completed. (Photo below shows the 183KE sedimentation basin work). Many ancillary facilities and waste sites in the 100K area have been demolished or remediated as well. (First photo shows this work).