LEM

LIQUID EFFLUENT MONITORING SYSTEM

The LEM system allows to sample the liquid effluents and to perform a gross gamma measurement of the samples in Marinelli geometry. The system is designed to survey the activity released through liquid effluents, performing the calculation of volumetric activity of the samples.

LEM system is composed of the following main parts:

  • Mechanical structure: stainless steel stand
  • Electrical and command board with panel PC and PLC: integrated in the stand and equipped with safety switch
  • Measurement system: NaI(Tl) detector, single channel analyzer PAD, 3 l Marinelli, 10 cm lead shielding well
  • Sampling circuit and self-priming pump
  • Software for system management, data acquisition and processing, failures and alarms indication

From the PLC based control unit it is possible to command the sampling circuit. The system is equipped with a touch-screen operator panel.

The PLC automatically manages all the cycle steps, and it constantly checks the proper functioning of the system, eventually communicating to the management software the error messages.

 
From the software it is possible to visualize in real time the measurement, to control the system’s status, to set the operative parameters, to manage the measurement steps, and to interact with the PLC to program the cycle (i.e. once a day at a defined hour) or to manually activate it. Alarm, prealarm and failure conditions (low flow, pump malfunctioning, detector fail) are indicated by the management software through the screen.

The system visualizes the volumetric activity and the total activity, or the count rate and integrated counts.

The operator can set and save on non-volatile internal memory the threshold values and the operative parameters through a keyboard; to access all these functions, a safety password is required. The LEM system saves and archives all the alarm events.


Additional Info

  • Main features:
    • Measurement geometry: 3 liters Marinelli Beaker
    • Detector type: 2”x2” Nal(Tl) scintillator
    • Shielding: lead well, 10 cm thickness
    • Panel PC and PLC for sampling circuit command and alarm output
    • Management software
    • Ethernet interface available
    • Efficiency calibration function for reference radionuclide
    • Fault and alarm statuses indication
    • Alarm events saving and archive
    • Efficiency in measurement geometry: >1.5% (Cs-137)
    • Energy range: 50 keV – 2 MeV
    • Measurement range: 3.7 103 (MDA 5 min) – 3.7 108 Bq/m3
    • Optional sources for quality control and calibration

     

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