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The Thorp nuclear fuel reprocessing plant at Sellafield, Cumbria, in the U.K. has been closed. No more spent nuclear fuel will be reprocessed there. Now the plant will undergo decommissioning which will require decades and billions of dollars. In order to successfully and safely dismantle and decontaminate the plant, it will be necessary to develop some new technology.
Five sieverts of radiation absorbed in an hour is considered enough to kill a human being. The Head End Shear Cave (HESC) section of the Thorp facility is where the spent nuclear fuel rods are removed from their fuel rod assemblies and cut into sections. Then the sections are dissolved in hot nitric acid. The radiation level in the HESC is two hundred and eighty sieverts per hour, far above a lethal dose of radiation.
The only way to dismantle and remove this equipment is with the use of robots. Once that has been accomplished, water and acids will be used to wash out the room and lower the level of radiation. It is hoped that it can be made safe enough for human beings to enter. New decontamination washing agents may have to be developed.
It will require robots and remotely operated vehicles to clean up other parts of the plant. It is hoped that such systems in use in other industries such as oil and gas, car manufacturing and even space industries can be adapted for the Thorp decommissioning. However, some of the needed systems will have to be developed from scratch. Very small robots which are able to change shape may be needed to go through small apertures to get into some of the contaminated areas. On the other extreme, very large mobile platforms might be needed to move around other equipment.
There other facilities that have been or are being closed in the Sellafield site. These other facilities are also very heavily contaminated. The equipment being developed for the Cave decommissioning will be of use in the dismantling and decommissioning the other facilities.
A flying drone has already been used to map radiation contamination in parts of the site that are difficult or impossible to access via usual methods. Remotely operated robot submarines have also been used to explore and begin cleaning up old storage ponds that contain radioactive materials.
There is a large network of specialist companies which will be developing the machines necessary to decommission the Thorp facility and other facilities on the Sellafield site. Many of these companies are located in Cumbria.
There is a growing business in the U.K. to decommission old nuclear reactors and other facilities such as Sellafield. Almost five hundred nuclear facilities scattered around the U.K. are slated to be decommissioned in the next forty years.
The Centre for Innovative Nuclear Decommissioning Engineering was just opened in Workington, a community in Cumbria. The Center will assist in the research and development of new decommissioning technologies to help with the decommissioning work at Sellafield. It is hope that research at the Centre and experience at Sellafield will help the U.K. export decommissioning services to other countries.