A Review of the Different Methods to Quantify Tritium Inside Waste Drums via Helium-3 Mass Spectrometric Measurements

This work deals with an indirect and non destructive measurement of tritium in solids. Instead of measuring tritium, we propose to measure the production rate of the decay product: ³He.

The amount of tritium enclosed inside a waste drum can be determined with an adapted ³He ingrowth method that takes into account the leak rate of the drum. The model leads to different ways to quantify tritium in the drum. It is confirmed using reference drums that measuring the ³He leak by confining the drum during its equilibrium state gives the same result as sampling the drum atmosphere at the beginning of the storage. For each method, the appropriate apparatus, experimental procedures and calculation of tritium activity from mass spectrometric ³He measurements are detailed. Performances of these techniques are studied and discussed.

In addition, we describe a novel and fully automated apparatus based on the confinement method that makes it possible to achieve a close tritium inventory of all the waste drums stored or produced at CEA Valduc.