4. Conclusion

Neutron radiography experiments have shown that sufficient neutron flux can reach the interior of a subsea pipeline (single or double) despite the combined thicknesses of a steel pipe and syntactic polypropylene insulation. This flow of neutrons through the pipeline walls activates the materials present in the pipeline, namely the hydrocarbons and their hydrates as they form. The resulting gamma emission is able to pass through the pipeline wall, and its intensity, particularly on the hydrogen peak of the gamma spectrum, is high enough to be measured in a few seconds. Attenuation due to surrounding seawater has also been studied to control its effects on signal intensity and ensure satisfactory detection of hydrocarbons and hydrates. The technique developed above also makes it possible to highlight the first instants of hydrate formation in pipelines.

All these...