Depth Profiling of Contamination Distribution: Non Invasive Solutions

Key Drivers

• Map the in depth contamination distribution in walls and floors when a non-invasive method is required.
• Ensure worker safety in efficiently applying ALARA principles and mitigating risks.
• Optimize financial cost with an upstream assessment of waste volumes and subsequent disposal costs prior to any dismantling field work.
• Collect all relevant data, before and during field work, allowing optimization of:
  • The choice of the most efficient dismantling tools, techniques, methods
  • Field work duration
  • Waste sentencing

Key Benefits

• Field Work Time Reduction
• Dose Exposure Reduction
• Cost Reduction of total project

Objectives

• Accurate characterization of in-depth contamination distribution in homogeneous and non-homogeneous mediums (walls, slabs, concrete…)
• 3D mapping of contamination allowing waste volume calculation per category
• Gamma activity measurement
• Provide customers with versatile solutions to perform:
  • Accurate upstream mapping of contamination
  • Fast in-situ measurements during D&D operations
  • Rigorous final verification measurements

Concrete wall measurements with CZT or HPGe detectors

Technical description

Surface measurement of concrete can be carried out by a simple ISOCS™ instrument measurement. For depth profiling measurement, three non-invasive methods are available:

1. Outside Wall using the ISOCS system, take one measurement if using multi-energy line nuclides
   • Non-invasive.
   • HPGe ISOCS based.
   • Needs multi-energy nuclide e.g. ¹⁵²Eu, ²³⁸U, ²³⁵U, Ra+d, Th+d, even ¹³⁷Cs (surface) or ⁶⁰Co (in depth) as reference, most of them were well calibrated, to determine the contaminated isotope and activity on depth profile.
   • ISOCS system efficiency calibrations.
   • Advanced In-situ Gamma Spectrometry (AIGS) Services.
2. Outside Wall using the ISOCS system, take three measurements if using single energy line nuclides
   • Multiple measurements at different angles.
   • ISOCS based collimated detector.
   • Can use simpler nuclides or with single energy line nuclides to determine the depth profile of contaminated sources.
   • Best result is when all spectra have the same activity at all energies.
   • Advanced In-situ Gamma Spectrometry (AIGS) Services.
3. Outside Wall using the ISOCS system in-situ and spectrum shape data
   • Based on increased Compton down-scatter for activity at deeper locations.
   • Calibration based on Peak-to-Compton ratio as a function of depth.
   • Sophisticated algorithms implemented in software.

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