Studies of Radiation damage in Nuclear Structural Materials by Particle Irradiation using Accelerator

The structural materials in nuclear reactors suffer extensive radiation damage causing a problem of structural integrity. Therefore, it is essential to study the degradation of these materials primarily due to irradiation.

Scope : We have carried out radiation damage studies on different nuclear structural materials using the beam of Variable Energy Cyclotron at Kolkata. The nuclear structural materials used in these studies were primarily Zirconium and its alloys, Stainless Steel and Ti and its alloys. These alloys are important nuclear structural materials used in either PHWR and Fast Breeder Reactors. In near future, Superconducting Cyclotron and DAE Medical Cyclotron are being commissioned in Kolkata. Superconducting Cyclotron will render high energy heavy ions. These heavy ions will have large penetration depth within the target material and will provide considerable damage rate. This will help us to study the effect of radiation damage in the bulk samples. Moreover, it will facilitate the simulation of damage caused by fission fragments in the reactors. Medical cyclotron will provide proton of 18-30 MeV with high beam current up to 350 mamp, which will cause effective damage at a very short time.

The studies on nuclear structural materials which are essential to carry out, will be with respect to structural changes (like phase segregation), microstructural changes, changes in mechanical properties like U.T.S, Y.S., percentage elongation, ductility and fracture toughness. These studies are needed to be carried out systematically as a function of fluence using different ion species. Studies on recovery of radiation induced damages will also be carried out at different temperatures.

Keeping these ideas in view, we propose the following studies (in addition to the above-mentioned studies) which are essential for radiation damage programme:

Radiation-induced diffusion of defects species in the irradiated materials and its modeling

Radiation induced phase segregation

Modeling material behavior under irradiation, and the relationship between changes at the atomic scale with changes in the mechanical properties under irradiation using molecular dynamics and Monte-Carlo simulation

The structural materials to be considered for radiation damage studies are Zircaloy-2, Zr-2.5%Nb, Zirlo, D9, D9I and Stainless Steel. Among them, Zircaloy-2 and Zr-2.5%Nb are used as fuel cladding and pressure tube materials respectively. Zirlo is a candidate structural material for fuel cladding tube to obtain high burn up. D9 and D9I will be used as the core components of PFBR. Stainless Steel is one of the important core components for breeder reactors. We will also be involved in the assessment of the damage suffered by the target materials like T-91 and HT-9 to be used in the ADS program.

Project Co-ordinator : Dr. P. Barat

Email : pbarat@veccal.ernet.in