Abstract: A method for measuring the fixed contamination level in a confined area such as small diameter pipe. The method measures the accumulated detection response over a given area and prescribed time period. To obtain the measurement a plurality of sensors are connected in tandem to form a flexible detector string and remotely positioned within the area to be monitored. The measurement is correlated to a standard obtained by using a known source in a simulated mockup environment. In one embodiment a passive monitor such as a Thermo-Luminescence Dosimeter is employed as the sensor.