After 30-40 years,nuclear power plants need to bedecommissioned(development of cracks in the structure,safety issues)
Cleaning of concrete walls(concrete scabbing)
Cleaning of contaminated pipes before dismantling
Cobalt-60 deposits on feeder pipes(half life 7 years)
Stainless steel needs to be recycled
Other methods such as mechanical scabbing and water jettingproduce a lot of waste
Corrosion of the metal pipes releases the products into reactorcoolant.The suspended metals are transported into the activearea and get radioactive.Subsequently they get deposited onthe heat transport pipes and tubes in the form of oxides.
Laser cleaning of these pipes are required to reduce thecontamination level.
The transition metal oxides are transparent to near-IR so thelaser radiation passes through them and heats the metalunderneath.The high temperature vaporizes the metal andgenerates a shock wave which cracks the metal oxide andejects it out with a large force in a process called spallation.