The N Reactor was cocooned in June 2012. The above photo is the N Reactor from April 2022.
N Reactor was the last of Hanford’s nine plutonium production reactors to be built. It was called a dual-purpose reactor; it not only produced plutonium for America’s defense program but it also generated electricity. At the time it was the only reactor of its kind in the country.
N Reactor was so revolutionary that then-President John F. Kennedy visited Hanford in 1963 to commemorate the start of plutonium production operations and break ground for the power-generating component of the facility.
The technology associated with N Reactor was far superior to that used in the first eight nuclear reactors at Hanford. N Reactor had a state-of-the-art cooling system that required significantly less water from the Columbia River to cool it during operations. The reactor was also built with a safety system that would automatically shut down the reactor in the event of a cooling water loss.
N Reactor operated from 1963 until 1987, when it was shut down for routine maintenance, refueling and safety upgrades. However, it was never restarted. Instead, the Department of Energy placed the reactor in standby status, which led to its eventual shutdown without ever going operational again. With more than 24 years of service, N Reactor was the longest-running reactor at Hanford.
When N Reactor was shut down, 1 million gallons of contaminated water were left in its storage basin, along with approximately one-third of Hanford’s supply of irradiated uranium fuel rods. Workers removed the water and sent it to Hanford facilities where it was treated and safely disposed of. The remaining irradiated fuel segments were placed in the K Basins and have since been moved to the Canister Storage Building, where they will stay until such time as a national repository can accept them.
In June 2012, N Reactor was placed in Interim Safe Storage, a process known as “cocooning.” As part of cocooning, workers removed all ancillary buildings and sealed up the reactor. The N Reactor cocoon, the largest at Hanford to date, encloses the reactor building (85,450 square feet) and steam generators used to produce electricity.