The thesis presents the design process and numerical analysis of a manipulator component used in nuclear power plant inspections. Inetec - Institute for Nuclear Technology designed the Forerunner, a manipulator used for steam generator inspections in PWR nuclear power plants. The Forerunner uses four specifically designed grippers to lock his position on the steam generator tube sheet. In the gripping process, an elastic component of the gripper, called the gripper finger, is pushed into the tube. Through a pneumatic actuator, the finger then expands and locks to the tube. In the nuclear industry it is recommended to use equipment that consists of as few components as possible. Since the Forerunner gripper finger used a mechanism with three components, a new gripper finger with only one component was designed. In the introduction of the thesis, a short overview of nuclear power plants was provided. Basic nondestructive testing methods and current robotic system used in nuclear power plant inspections were shown. The inspection process was explained on the Forerunner. One chapter was dedicated to explaining basic theory concepts used in numerical analysis of problems that include large strains and contacts. The basics of nonlinear formulation and contact modeling in the software suite Abaqus FEA was provided. After presenting the used modeling techniques on a simple verification problem, an overview of the design process of the new gripper finger was given. The design process was accompanied with the appropriate numerical analysis using the finite element method. Based on the results of the numerical analysis, the new gripper finger was manufactured and tested in Inetecs laboratory, where it was shown that the new design of the gripper finger meets all the necessary demands and reliably works within the expected number of locking cycles.