We have developed two  'Gamma Eye' instruments for measuring the much larger bulk gamma emissions from, for example, material contaminated with NORM (Naturally Occurring Radioactive Material) scales, soil contaminated with fission products – using 137Cs as a marker and redundant concrete shielding – using activation 60Co as a marker.

These instruments are ideal for sites where significant quantities of gamma contaminated material need to be assayed and segregated within a short time frame. The dirt associated with mined coal contains significantly higher concentrations of the naturally emitting radio-nuclides 40K and the Uranium & Thorium series than the coal itself.

A sensitive gross gamma sensor can be calibrated to provide a measurement of the ash content based upon the concentration of these trace radioisotopes in the dirt. Hundreds of Bretby Gammatech systems are in everyday operation in over 200 countries around the world.

Both these instruments have been developed by our technical team in close association with Nuvia Ltd:

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GammaEye – benefits

  • Quick & easy assessment of gamma contaminated material
  • Fast throughput (one tonne per minute)
  • Reduced measurement time leading to reduced time on site
  • Reduced reclamation costs

How it works

The digger driver lowers the bucket onto the monitor frame and once in position the system automatically makes its measurement. After 10 seconds or so one of three lights illuminate – Green for OK, Amber for medium activity and Red for higher activity.

The digger driver can then deposit his load in the appropriate place for subsequent disposal or processing. 


The accuracy of the Heat Eye will depend upon the site and the performance of each component sensor. Accuracies of (1 sigma) better than 0.5% on final product and between 1 and 3 % ash with run-of-mine (ROM) have been achieved with production systems.

Precisions in the order of 0.5% are regularly being achieved with final product monitors (Measured to ISO 15239)

GammaEye –  features

  • Easily calibrated for a range of gamma contaminants
  • User selectable alarm levels
  • Automated initiation of counting
  • Simple traffic light system to indicate alarm level reached
  • Safe operation as no personnel need to be close to take meter readings
  • Log of measurements maintained which can be downloaded to a PC
  • Easy to generate and update background
  • No moving parts
  • 24 hour battery operation, powered by rechargeable sealed lead acid battery units
  • Easy to transport around site


  • Clearance of potentially contaminated land sites
  • Remediation work during industrial building work
  • Preparation for major housing developments
  • Sorting and separating debris for disposal

Download the GammaEye brochure

Printed brochure available upon request.