Abstract: large number of radioactive contaminated hydraulic torque wrenches are resulted from maintenance of radioactive contaminated equipment and sites during normal operation and outage of nuclear power plants. And the contaminated hydraulic torque wrenches are difficult to be decontaminated because of their complex structure with many components and hot spots deposited in dead corners. Therefore they have to be treated as radioactive waste in many nuclear power plants. In order to solve the problems regarding cost control, minimization of radioactive waste, and radiation protection optimization caused by these contaminated hydraulic torque wrenches, some deep decontamination tests through chemical decontamination, mechanical decontamination, foam decontamination, ultrasonic decontamination and other combined processes were carried out. Result shows several hydraulic torque wrenches are finally cleaned and qualified with decontamination criteria after four stages of deep decontamination with a decontamination factor of higher than 1,000, which proves the deep decontamination method for radioactive contaminated hydraulic torque wrenches is feasible, practical and effective.

Key words: radioactive contamination, torque wrench, deep decontamination, chemical decontamination, ultrasonic decontamination