Preparation and Characterization Nickel and Iron Mixed Oxides for the Development of a Fuel CRUD Analysis Technique

Since the extended burn-up programs for a long-term fuel cycle were introduced in Pressurized Water Reactors (PWRs), safety and efficiency concerns have arisen due to a substantial increase of Chalk River Unidentified Deposits (CRUD) on the fuel surface. This fuel CRUD has been reported to create an axial offset anomaly (AOA) phenomena and an increase in the dose rate. At present, many approaches have been developed to mitigate the formation of fuel CRUD. In particular, the chemical analysis of fuel CRUD is an important subject relative to the determination of optimal reactor coolant chemistry. Recently, the development of a new analysis technique using laser spectroscopy commenced for the analysis of fuel CRUD. In developing this technique, it is essential to establish the emission spectrum database of CRUD samples with various chemical compositions. In the present study, we prepared five simulated CRUD samples with different Ni/Fe ratios. These were synthesized by a hydrolysis of nickel nitrate and iron nitrate mixed solutions and were heat treated under a high temperature steam condition. Their structures and elemental ratios were determined using Energy Dispersive Spectrometer (EDS), X-ray Diffraction (XRD) patterns, and Fourier Transform Infra-Red Spectrometer (FT-IR) approaches, respectively. We confirmed the formation of nickel ferrite