OXIDATION BEHAVIOR AND MICRO STRUCTURE ANALYSIS OF NUCLEAR GRAPHITE IG-110 AT 520℃ UNDER AIR ENVIRONMENT

Herlina Herlina,Abu Khalid Rivai,Sigit Tri Wicaksono

doi:10.12962/j2746279x.v2i1.9729

Abstract

Graphite IG-110 is a nuclear graphite structural and moderator material that has been used for high temperature gas cooled reactors (HTGR). Under normal operating conditions or accidental entry of air or water (air ingress or water ingress), a nuclear graphite. Therefore, the aim of this study is to investigate the oxidation resistant and microstructure change behavior of graphite IG-110 at high temperature under air environment. The sample of IG-110 was tested using Magnetic Suspension Balance (MSB) to analyze the weight change by in-situ for 420 minutes at a temperature of 520 o C. Morphological and microstructure analysis was carried out by optical microscope, SEM-EDS (Scanning Electron Microscope –Energy Dispersive X-ray Sprectroscope) and XRD (X-Ray Diffractometer). The results showed that Graphite IG-110 has a change in surface structure caused by the reaction of the material with oxygen in air at high temperatures. Furthermore, the crystal size of the material structure was slightly change. However, in general, the corrosion rate of graphite IG-110 at a temperature of 520℃ under the air environment is relatively low. So that if graphite IG-110 is exposed to air at a temperature of 520℃ for several hundred minutes in a nuclear reactor estimated does not suffer serious damage

Highlights

Nuclear grade graphite is commonly manufactured from a filler coke and pitch binder
The profile of oxidation testing of IG-110 graphite is shown in Fig. 1 The graphic shows the relationship between weight change with temperature and exposure time
In general the corrosian rate of the sample was 7x10-5mg/cm2/minute. It means that the corrosion rate of IG-110 at temperature of 520oC under air environment was relatively small

Summary

Introduction

Nuclear grade graphite is commonly manufactured from a filler coke and pitch binder. It manufactured from isotropic cokes (petroleum or coal-tar derived) and are specially formed to make them near-isotropic or isotropic materials from a highly isotropic (Windes et al, 2007). The macroscopic dimensions of nuclear graphite undergo 3-4% shrinkage and will increase during high temperature irradiation (Kurpaska et al, 2020). At hightemperature and under neutron irradiation environment porosity of nuclear graphite plays a very important role (Huang et al, 2019). A nuclear graphite has excellent irradiation performance and adequate mechanical properties at high temperatures it has been used extensively for moderators, reflectors, and structural materials for hightemperature gas-cooled reactors (HTGRs) (Zhu et al, 2017). Oxidation of graphite fuel elements in HTGR leading to exposure of fuel particles to oxygen and potentially followed by release of fission products (Joshua et al, 2017)

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