US Hanford nuclear plant is degrading, environment at risk
12 July 2019
A new report from the US Department of Energy has said that a plant at the Hanford nuclear site in the State of Washington is at risk of releasing radioactive contamination into the environment. The PUREX (Plutonium Uranium Extraction) plant is heavily contaminated having been used to produce plutonium for the US defence programme up until the 1980s.
The Hanford site’s PUREX plant – Image: Hanford.gov
The Hanford site, located 200 miles from Seattle, is considered to be the most contaminated nuclear site in the USA.
The federal report includes a risk evaluation of the PUREX plant and found that contamination is spreading through the facility as it degrades. In addition to the PUREX plant, several highly contaminated rail cars used to transport irradiated fuel rods are also temporarily buried nearby. As with the other Hanford structures, PUREX is slated to be decontaminated, demolished, and some of its debris removed. Similarly, the rail cars are also set to be decontaminated, removed, and permanently buried. The option of grouting the rail cars in-place within the tunnel is also being evaluated since removal of the cars would entail extreme worker safety hazards and would be more expensive.
According to the Tri-City Herald, a decision on how to go about cleaning up the Hanford site and demolish the PUREX plant is not expected until 2032 due to other, higher priorities at the site that require attention first. The new evaluation by the Department of Energy suggests that in the meantime, the best option is to spend $218 million to remove hazards, prepare the main processing building for demolition and demolish two attached annexes. However, the Herald says this would depend on whether funds are available and if the work would fit in with the other clean-up priorities.
The report suggests that a contamination leak could occur due to a fire or a break in a utility pipe, containment wall or the roof as the plant ages. In May 2017, hundreds of workers at the Hanford site were forced to take cover after a tunnel containing highly contaminated materials collapsed. Workers were told to shelter-in-place, secure ventilation to buildings and refrain from eating or drinking while others were told to evacuate the site following the incident.
The contamination risk at the PUREX plant, the main plant at the Hanford site, is great enough that action should be considered now to prevent a release, according to the risk evaluation. The PUREX plant is made up of a main building, also called a ‘canyon’ due to its long, high interior, and two annexes. It is one of five canyons at the Hanford site which was deactivated in 1998.
The report makes a number of suggestions on how to reduce the risk of a contamination release from the PUREX plant. At a cost of $218 million, this would include removing or stabilising hazards in the canyon, decontaminating or stabilising the contamination in the annexes, draining fluids from piping, removing overhead utilities and tearing down parts of the interior. As well as decreasing the chance of a contamination release, this work would also help reduce maintenance and surveillance costs at the site and make future clean-up operations less complicated. The report says that all the suggestions should be put into effect now in order to protect both people and the environment.
However, the current focus at the Hanford site is treating around 56 million gallons of contaminated waste which is currently held underground at the facility. Maintenance work has been done on all of Hanford’s canyons, but demolition has begun on just one – U plant. Used for training and recovering uranium from waste at other plants, U plant could be used as a model on how to demolish the other canyons.
No plan has been approved for the demolition of the other four canyons at Hanford yet. The Department of Energy is currently accepting public comments on the clean-up operation before issuing a decision on a clean-up plan later this year.