Coated Cladding Behavior During High-Temperature Transients

Abstract

The concept of accident-tolerant fuels has been proposed and widely investigated over the past decade. The contribution is focused on one of the near-term approaches -the modification of the surface of existing Zr-alloy claddings by protective coatings. The studied specimens are based on Zr-1%Nb substrate with chromium coating, multicomponent chromium nitride and chromium coating and multi-layer chromium nitride/chromium coating deposited by a physical vapor deposition process. Thermomechanical tests were designed to understand the cladding deformation and the burst conditions during the LOCA phenomena. Presented results show both the positive and the negative effect of coating on cladding behavior. All coatings exhibited a reduction of ballooning size and prolongation of time to burst. On the contrary, coating can be connected with larger opening size after burst, higher hydrogen content and deterioration of the local mechanical properties.

Experimental Study of Damaged Cr-Coated Fuel Cladding in Post-Accident Conditions

“…Regarding the accident conditions, the positive impact of Cr coating has been presented. Reduced deformation leading to a decelerated ballooning process as well as prolongation of time to burst was observed [8].…”

Applicability of Nuclear Fuel Safety Criteria to Accident-Tolerant Fuel Designs

“…Under accident conditions, anticipated benefits include enhanced high temperature oxidation resistance resulting in reduced energy release from the exothermic metal-water oxidation reaction, potentially lowering peak cladding temperatures, improved residual post-quench ductility due to less oxygen embrittlement, and reduced combustible gas generation. Another important anticipated benefit is reduced high temperature creep and ballooning and potentially smaller burst opening size [23,27,28,32,33].…”

Application and Development Progress of Cr-Based Surface Coatings in Nuclear Fuel Element: I. Selection, Preparation, and Characteristics of Coating Materials

“…At present, the most extensively used preparation methods of the Cr-based coatings on Zr alloys are physical vapor deposition (PVD) [14,[18][19][20]22,23,55,[104][105][106]108,109,115,116], cold spraying (CS) [15,24,73,95,107,[117][118][119], and 3D laser melting and coating (3D-LMC) [6,17,25,33,34,69,120]; each are currently used by CEA (French Alternative Energies and Atomic Energy Commission) in France, Westinghouse Electric Corporation in the US, and KAERI in South Korea, respectively. These preparation methods and the characteristics of the prepared coatings are described in the next section.…”