HIGH-TEMPERATURE STEAM AND AIR OXIDATION OF CHROMIUM-COATED OPTIMIZED ZIRLO™

Gauthier Bourdon,Martin Ševecek,Ladislav Cvrček,Jakub Krejčí

doi:10.14311/app.2019.24.0001

Abstract

The presented study focuses on Cr-coated cladding material and its oxidation performance in high-temperature steam and air. As the substrate material, Optimized ZIRLO™ was used which was coated by chromium using unbalanced magnetron sputtering. The experimental methods are described and the presented results focus mainly on weight gain and oxidation kinetic evaluation. The experiments were carried out in the high-temperature range between 1000 and 1300 °C. The test conditions focus mainly on the air oxidation tests that are relevant for some of severe accidents with air ingress and have not yet been studied in detail and are not available in literature. These data are supported with steam oxidation data to directly compare the kinetics in two different oxidizing environments.

Highlights

Since the Fukushima-Daiichi accident in 2011, new nuclear fuel and cladding materials have been investigated and developed to further enhance safety of currently operated Nuclear Power Plants
The oxidation kinetics can be first described by a parabolic law (Eq 2) where the value of n is 2. k1 is the rate of oxidation in mg.dm−2.min−1/2
The study presented clearly shows that chromium Physical Vapor Deposition (PVD) coated cladding samples have a better resistance to high temperature oxidation than uncoated ones in both steam and air for design basis accidents (DBAs) as well as DEC conditions

Summary

Introduction

Since the Fukushima-Daiichi accident in 2011, new nuclear fuel and cladding materials have been investigated and developed to further enhance safety of currently operated Nuclear Power Plants. They are called Accident Tolerant or Advanced Technology Fuels. When there is an accident with air ingress in a reactor core, a spent fuel pool [3] or in transportation cask, cladding strongly oxidizes in air or steam/air mixture. This causes release of heat as well as acceleration of cladding degradation and progression of accident scenario. Many coating materials have been studied so far, but the most promising seems to be material coated with pure chromium or Cr-based materials

Results

Discussion

Conclusion