Int J Advanced Design and Manufacturing Technology, Vol. 11/ No. 2/ June - 2018 39 © 2018 IAU, Majlesi Branch Preliminary Analysis of the Cladding Mechanical Behavior of a Nuclear Superheat Boiling Water Reactor Majid Bahonar Department of Nuclear Engineering, Science and Research branch, Islamic Azad University, Tehran, Iran. E-mail: majid_bhnr@yahoo.com Gholamreza Jahanfarnia* Department of Nuclear Engineering, Science and Research branch, Islamic Azad University, Tehran, Iran. E-mail: rezajahan@yahoo.com *Corresponding author Morteza Gharib Department of Nuclear Engineering, Science and Research branch, Islamic Azad University, Tehran, Iran. E-mail: mgharib2@yahoo.com Received: 30 January 2018, Revised: 19 February 2018, Accepted: 7 May 2018 Abstract: In the present study, investigation of mechanical behaviour of the fuel cladding material for a nuclear superheat Boiling Water Reactor with annular fuel rods, is carried out. In this design, each annular fuel element is cooled internally by steam and externally by water. For the fuel cladding material, radiation embitterment and irradiation-assisted stress corrosion cracking (IASCC) are the most important issues that have to be taken into account. Hence, for cladding, two materials are considered. Preliminary thermal expansion and stress analysis have been done for a fresh (begin of cycle) ASBWR (Annular-fuelled Superheat Boiling Water Reactor) fuel element. The purpose of these analysis is to investigate the stress distribution and thermal expansion of the cladding in the initial phase of operation. The results show that there is a noticeable difference in the axial expansion between the inner and outer claddings. For T91 (modified 9Cr-1Mo steel) cladding, the maximum axial thermal growth of the inner cladding is 22.12 mm, which is about 9.7 mm more than the outer cladding. For Inconel 718 cladding, the results are 27.8 mm and 13.4 mm, respectively. Keywords: Annular fuel, Strain, Stress, Superheat BWR, Thermal expansion Reference: Bahonar, M., Jahanfarnia, Gh., and Gharib,M., “Preliminary Analysis of the Cladding Mechanical Behavior of a Nuclear Superheat Boiling Water Reactor”, Int J of Advanced Design and Manufacturing Technology, Vol. 11/No. 2, 2018, pp. 39-45. Biographical notes: Majid Bahonar received his PhD in Nuclear Engineering from IAU, Science and Research Branch, in 2017. His research interests include power plant technology, Reactor thermal-hydraulic and safety analysis, and two phase flow. Gholamreza Jahanfarnia received his PhD in Nuclear Power Plant from University of Moscow, in 2005. He is currently Professor at the Department of Nuclear Engineering, science and research branch University, Tehran, Iran. His current research interest includes power plant technology and two phase flow. Morteza Gharib is Associate Professor of Nuclear engineering at the Amirkabir University and IAU, Iran. He received his PhD in Nuclear engineering from Pensylvania University of USA.