Tri Dasa Mega Vol. 23 No. 1 (2021) 21–32 JURNAL TEKNOLOGI REAKTOR NUKLIR TRI DASA MEGA http://jurnal.batan.go.id/index.php/tridam JOURNAL OF NUCLEAR REACTOR TECHNOLOGY TRI DASA MEGA Jurnal Teknologi Reaktor Nuklir Tri Dasa Mega Journal homepage: jurnal.batan.go.id/index.php/tridam Strain Analysis of Reactor Type Core Structures by Considering Uncertainties of Graphite’s Properties Mike Susmikanti 1* , Roziq Himawan 2 , Jos Budi Sulistyo 3 , Farisy Yogatama Sulistyo 1 . 1 Center for Nuclear Reactor Technology and Safety (PTKRN Batan), Kawasan Puspiptek, Tangerang Selatan, 15310, Indonesia 2 Center for Informatics and Nuclear Strategic Zona Utilization (PPIKSN Batan), Kawasan Puspiptek, Tangerang Selatan, 15310, Indonesia 3 Center for Nuclear Facilities Engineering (PRFN Batan), Kawasan Puspiptek, Tangerang Selatan, 15310, Indonesia ARTICLE INFO A B S T R A C T Article history: Received: 26 December 2020 Received in revised form: 28 January 2021 Accepted: 5 February 2021 The power reactor with high-temperature gas-cooled reactor (HTGR) technology uses uranium as the reactor fuel. The energy from fission is converted to electrical energy or used for other needs such as hydrogen production or other research activities at high temperatures of around 700 C. This operation does not allow the use of metal as the core material for the reactor. The material that fits the requirements as a core structure is graphite. Graphite material has specific characteristics, namely the parameters of the modulus of elasticity, coefficient of thermal expansion, and the volume which changes due to temperature and neutron dose. Because the structure of the reactor core is a vital component in the reactor, this research will develop a method for the design of the reactor core structure with graphite material. The design method is based on "Design by Analysis" which specifically refers to the strain analysis on each of the reactor core components. The design method developed is based on the finite element method. The object of this research is the side reflector made from the Toyo Tanso IG-110 series graphite. Based on the analysis of heat distribution and heat stress for the material before the effect of neutron exposure, the temperature distribution on the side reflector was found, as well as the displacement and heat stress that occurs isotropic properties, Young's modulus and Poisson’s ratio values can be verified and estimated. The purpose of this research is to analyze the strain of the reactor core structure by taking into account the uncertainty of the graphite properties. Keywords: Strain Analysis HTGR Graphite IG-110 Probabilistic Analysis © 2021 Tri Dasa Mega. All rights reserved. 1. INTRODUCTION  The High temperature gas cooled reactor (HTGR) was chosen because of its inherent safety characteristics, it will automatically extinguish any uncontrolled reactions. Unlike the light water- cooled reactor types, the pressurized water reactor (PWR) and the boiling water reactor (BWR), the HTGR is designed to operate at a high temperature of 700 0 C as shown in Figure 1. In addition to its  Corresponding author. Tel./Fax.:021 756 0912/756 0913 E-mail: mike@batan.go.id DOI: 10.17146/tdm.2021.23.1.6172 safety characteristics, the HTGR has another advantage in that it can be used in cogeneration by utilizing residual heat from steam generation.