Non-destructive inspection method for lining tank, non-destructive inspection system, and control program

A non-destructive inspection method for a lining tank, the method comprising:

• a heating step of heating a measurement region set on an outer surface of the lining tank by heat generation of a heat input means;
• a step of acquiring, by a measurement means of an active thermography inspection system, a state information indicating a temperature or a temperature change of the measurement region during a cooling period after termination of heating;
• and
• a step of analyzing, by an analysis means of the active thermography inspection system, the state information to generate an analysis information indicating an internal state of the lining tank, wherein
• the heat input means and the measurement means are arranged, so that an angle formed between a line of action passing through a center of the measurement region and the heat input means, and a line for measurement passing through the center of the measurement region and the measurement means is in a range of approximately 7.5 degrees to 75 degrees or a range of 7.5 degrees to 75 degrees,
• a measurement distance between the lining tank and the measurement means is approximately 300 mm to 1200 mm or 300 mm to 1200 mm, and
• a separation distance between the lining tank and the heat input means is approximately 100 mm to 700 mm or 100 mm to 700 mm.