Published June - July 2026, Pg. 60-68

Section: Еcology and industrial safety

UOT: 628.31; 544.6; 539.16

DOI: 10.37474/0365-8554/2026-06-07-60-68

Changes in the wettability and absorption behaviour of radiation-induced pipe line sediments

M.A. Ponyakin - Azerbaijan State Oil and Industry University

This study investigates changes in the flow and wetting behaviour of complex deposits such as asphaltenes, paraffin, and corrosion products in pipeline systems under the influence of ionising radiation. Ionising radiation (gamma, neutron, etc.) fundamentally alters surface energies, creating irreversible changes in the molecular structure of materials, such as bond breaking and the formation of cross-links. Within the scope of the study, the effects of radiation-induced surface changes on contact angle, the effects of pore structure collapse on capillary suction dynamics, and, in particular, the critical effects of this phenomenon on flow resistance in nuclear facilities (such as the Akkuyu NGS) were analysed. The analyses show that radiation can transform hydrophobic deposits into a hydrophilic structure, leading to swelling of the deposits and deterioration of permeability. Therefore, it is emphasised that the effects of radiolysis and surface-fluid interactions at the molecular level must be considered to ensure flow safety in pipelines containing radionuclides.
The effect of ionizing radiation on deposits accumulated in pipelines is not limited to changes in chemical composition; it also causes transformations in surface free energy, contact angle, and the interaction equilibrium at the solid-liquid interface. Particularly in heterogeneous deposits consisting of asphalt, paraffin, and corrosion products, radiation-induced bond breaking, cross-linking, and accumulation of polar functional groups can cause surfaces that were initially hydrophobic to become more hydrophilic over time. This change causes the sediment layer to become more wetted when it comes into contact with the liquid, alters the way it adheres to the surface, and complicates its interactions with the inner surface of the pipe. Therefore, in the analysis of radiation-induced pipe interior deposits, not only mechanical blockage should be evaluated, but also the surface changes caused by radiation and their effects on wettability should be considered.
Another important effect of radiation manifests in the porous structure of the sediment layer and its capillary absorption behavior. Microstructural damage in the sediment structure can lead to narrowing or irregular expansion of the pores, which in turn affects the rate at which the fluid advances through the sediment. Furthermore, changes in fluid viscosity, surface tension, and interfacial equilibrium caused by radiolysis processes cause deviations from the classical behavior of capillary suction dynamics. This process can cause the sediment to acquire a structure that retains more moisture, swells, and becomes less permeable. As a result, the effective cross-section of the pipe narrows, pressure losses increase, and surface roughness increases further due to the effect of corrosion products. Therefore, sediments exposed to radiation should be considered not only as passive accumulation material but also as an active and variable porous medium that directly affects the flow regime.
In this context, changes in the wettability and liquid absorption properties of deposits in nuclear facilities, and particularly in pipelines carrying radionuclides, are directly important in terms of flow safety and operational continuity. Sediments that become increasingly hydrophilic under radiation and increase their water retention capacity negatively affect system performance by increasing the pumping load while also reducing heat transfer efficiency. In addition, prolonged contact between the liquid trapped in the sediment and the metal surface can accelerate local corrosion processes. On the other hand, sediment particles that become brittle or break off due to structural weakening can be transported along the pipeline, causing new blockages. To prevent such complications, mechanical cleaning methods alone are not sufficient for the safe operation of pipelines; the effects of radiolysis, changes in contact angle, increased moisture absorption tendency, and molecular interactions at the sludge-liquid interface must all be evaluated together. This holistic approach is critical for planning maintenance periods, selecting appropriate materials, and developing preventive monitoring strategies, especially in systems with high radiation environments such as the Akkuyu NGS.

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