Characterisation & Sorting

Due to the variations in storage costs for the different categories of radioactive waste, sorting can deliver a major cost advantage.

NRG has advanced equipment for the very accurate characterisation and sorting of radioactive waste. Much of NRG’s knowledge and experience has been gained at our own site in Petten, in the project involving the characterisation, sorting, separation, repackaging and disposal of ECN’s stored historic waste.

CHARACTERISATION & SORTING SERVICES

  • Non-destructive characterisation of radionuclides
  • Sorting from high-activity to low-activity material
  • Recommendation of optimal disposal routes for radioactively contaminated components and waste streams at national and international level


Nuclide identification
The segmented gamma scanner developed at NRG, VINISH (Visual Inspection and Nuclide Identification System for High -activity waste) characterises radioactive waste very accurately using high resolution gamma spectrometry. The characterisation is non-destructive, so that the waste drums can remain closed. By setting the collimators to the activity, both high-activity and low-activity waste can be measured. Besides the detector, the equipment also includes a camera to visually inspect the condition of the waste drum.

VINISH scans the material accurately by rotating the drum horizontally and vertically at the same time. The drums are placed in four or five different positions so that different parts are measured in each measurement. VINISH determines the activity of a number of nuclides, thus giving a clear picture of the contents of the drum.

Radiation map
To sort waste of mixed high-activity and low-activity waste based on radiation level, NRG developed the gamma scanner HIRARCHI which is set up in its hot cell lab. After the contents of a drum of radioactive waste are displayed on a table, they are scanned with a movable gamma detector.  In a few minutes, this creates a surface scan (‘radiation map’) of the activity (MBq/cm2). Areas on the table are then highlighted in colours based on the radiation level. This radiation map is calibrated such that the different colours correspond to the waste categories used by the waste storage facility (in the Netherlands, COVRA). Using the scans, the waste can be sorted according to the acceptance criteria of the relevant waste storage facility.

Photo: Camera image of the sorting table with radioactive waste, with the radiation map projected over it.

NRG REFERENCES

  • The historic Radioactive Waste Project Read more...
  • Engineering of an advanced measurement system for characterising radioactive components (VINISH). Read more...
  • Setting up an innovative sorting unit for high-activity, medium-activity and low-activity waste (HIRARCHI). Read more...
  • Setting up a waste registration software database.

 

Diagram: sorting historical waste on the Petten site