Nondestructive testing apparatus for blade root of steam turbine of power plant

A nondestructive testing apparatus for testing a blade root of a steam turbine installed in at least one of (a) a nuclear plant and (b) a thermal plant by using an ultrasonic probe, comprising:

• an ultrasonic probe fixing unit configured to test the blade of the steam turbine;
• and
• an encoder fixing unit configured to record a rotation distance of a rotatable turbine rotor;
• wherein the ultrasonic fixing unit includes a first magnetic body switchably fixed to a fixture supporter, a first steel shaft fixed vertically to the first magnetic body, a second steel shaft connected to the first steel shaft through a first joint and having a three-dimensional degree of freedom to be rotatable and vertically movable, a contacting pressure controller mounted to the second steel shaft configured to maintain a predetermined pressure between the ultrasonic probe and the blade, the ultrasonic probe mounted to a leading end of the second steel shaft by the contacting pressure controller and a second joint to directly contact the turbine rotor;
• and
• wherein the encoder fixing unit includes a second magnetic body switchably fixed to the fixture supporter, a third steel shaft fixed vertically to the second magnetic body, a fourth steel shaft connected to the third steel shaft by a third joint and having a three-dimensional degree of freedom to be rotatable and vertically movable, and an encoder mounted to the fourth steel shaft rotatably to measure a rotation distance of the turbine rotor.