Surface Contamination Monitor (SCM)

The SCM revolutionized the performance of contamination surveys when it was introduced more than 10 years ago.  Today it is widely recognized throughout the nuclear industry for its superior production rate while satisfying the DQOs of characterization and final status surveys.  It has consistently saved our clients time and money, while meeting or exceeding both site-specific and statutory performance criteria and minimizing the risk of future liability.

This state-of-the-art system uses a patented Position Sensitive Proportional Counter (PSPC) that is capable of establishing where along the detector an event occurs (NUREG/CR-6450).  This allows a long detector to be divided electronically into a continuous array of small, virtual detectors that are similar in efficiency to other counters, but have backgrounds associated with small area detectors.  This results in improved sensitively, due to low background, and specific identification of the location of the radioactivity.

The SCM may be operated in either rolling (dynamic) or static modes both of which can utilize large-area PSPCs.  In dynamic mode, the SCM logs information in 25 cm² bins by logging data for each 5 cm width of the PSPC and for every 5 cm of forward travel.  Scan speed is motor controlled and the distance the SCM travels is measured by a precision wheel encoder.  Data are recorded in 25 cm² pixels over the entire surface surveyed, thus the SCM records 400 measurements for every square meter it traverses.  Controlling the survey speed and automatically logging the location of the data obtained using a wheel encoder eliminates the errors and uncertainties associated with hand held detectors.  Furthermore, support wheels hold the detectors at a fixed height from the surface which eliminates uncertainty associated with scan height.  Static mode is used to survey areas that are generally inaccessible in dynamic mode, such as corners, stairs, and system components.

The enormous amount of survey data generated by the SCM is effectively analyzed and managed using our Survey Information Management System (SIMS).