Abstract
The buildup of fouling deposits in energy systems degrades their ability to transfer heat, reducing efficiency and causing operational issues such as localized corrosion. Each application presents its own challenges. In nuclear power generation, the buildup of CRUD (Chalk River Unidentified Deposits) induces unique, negative effects ranging from reduced heat transfer, to axial power shifting, to CRUD-induced localized corrosion (CILC), the last of which can cause sudden fuel failure. Knowledge of why CRUD forms and how to prevent its adhesion to nuclear fuel rods represents a major step towards eliminating it. This paper demonstrates a methodology to ascertain which materials may resist CRUD adhesion, thereby preventing its initiation and growth. It presents experiments targeted at multiple length scales: pool boiling (macroscale), which simulates CRUD initiation processes in a nuclear reactor, and atomic force microscope (AFM) force spectroscopy (microscale), which yields quantitative measurements of the adhesion between CRUD constituents and candidate CRUD-resistant materials. Early data from both sets of experiments show some correlation, suggesting that AFM force spectroscopy (AFM-FS) may be used to pre-screen materials for fouling resistance. So far, it appears that CRUD constituents adhere well to oxides, while carbides show both greatly reduced adhesion and no adherent CRUD in pool boiling experiments. The relationship between the AFM-FS measurements and the growth of CRUD in the pool boiling experiments may provide insight into the possible factors affecting fouling in nuclear reactors, eventually leading to its elimination.
