High-temperature oxidation kinetics of sponge-based E110 cladding alloy

Recent Advances in Protective Coatings for Accident Tolerant Zr-Based Fuel Claddings

“…The obtained results show similar oxidation kinetics of both alloys without breakaway effects. Yan et al showed that the oxidation kinetics of sponge-based E110 alloy accelerates with increasing temperature, and a good correlation with the Cathcart-Pawel prediction model [57] was observed at 1200 • C (Figure 1) [58]. The equivalent cladding reacted (ECR) parameter up to 17% of the initial cladding thickness was reached after 220-230 s at 1200 • C. Exceeding this value leads to a significant degradation of the mechanical properties of the fuel claddings, according to the criteria of the US Nuclear Regulatory Commission (NRC) [59].…”

“…Exceeding this value leads to a significant degradation of the mechanical properties of the fuel claddings, according to the criteria of the US Nuclear Regulatory Commission (NRC) [59]. [58] with permission by Elsevier.…”

FY21 burst activities with coated Zircaloy-4 under accident conditions

“…For the coated specimen, the surface roughness persisted through oxidation, so three oxide thickness measurements were taken at the minimums (valleys) and maximums (plateaus), as shown in Figure 3-11b. Optical microscopy is recommended for measurement of the alpha-Zr layer because it provides better contrast between the alpha and beta layers [30]. To determine if the coating had no negative impact on oxidation performance, the oxide layer measurements must be normalized to temperature, because zirconium-based alloy oxidations rates are known to depend strongly on temperature [30].…”

“…Optical microscopy is recommended for measurement of the alpha-Zr layer because it provides better contrast between the alpha and beta layers [30]. To determine if the coating had no negative impact on oxidation performance, the oxide layer measurements must be normalized to temperature, because zirconium-based alloy oxidations rates are known to depend strongly on temperature [30]. To verify if the unirradiated coating provided any protection from oxidation during a LOCA, the oxide layer measurements were compared to calculated oxide thickness from the temperature history of the thermocouple closest to oxide-measured location using the Cathcart-Pawal (CP) [31] relation integrated over the entire temperature history.…”

“…The oxide measurement for the uncoated Zry-4 material and the CrZr4 material in the valleys agreed well with the CP calculation, but the measured oxide layer of the CrZr4 material in the plateaus was 14% greater than the calculated thickness. More testing that more precisely controls and measures oxidation temperature like the procedure described in the article by Yan et al [30] would be required to confirm the oxidation performance of the coated material. Since no protection was expected from the coating, it is suspected that significant oxygen transport would occur, resulting in double-sided oxidation of the chromium coating (one side being the steam, and the other side being at the Coat/ZrO2 boundary).…”