In this paper, the strength test of the mobile constructor's structure is carried out, which is used during the irrational testing in nuclear power plants. The manipulator as part of the test system is used for ultrasonic and visual testing of one of the primary circuit components of a cylindrical nuclear power plant. Nuclear power plants are regularly subjected to irreversible tests to check their condition and lifetime estimates. Faults are very difficult to remove and as a result may be mixed with the water of the primary circuit (water that is in direct contact with the fuel elements of the nuclear reactor) with secondary circuit water passing through all the power points of the plant (steam turbine, capacitor). The consequence of such damage is very complicated to remove and require a very high investment and the exclusion of that block of power plant for a longer period of time. Nondestructive testing are performed by robotized systems instead of people due to high radiation, which increases the speed and achieves quality of inspection. The paper describes the process of obtaining nuclear energy used for power generation and the most important types of nuclear reactors that are an important part of the nuclear reaction. The test method and mobile manipulator used in this paper are explained. The finite element method and the Abaqus program package are described, in which the analyzes defined in this paper are made. Thereafter, the verifiable numerical model of the beam loaded with its own weight is shown, based on which the final elements are selected. The main part of the paper is the numerical analysis of the mobile manipulator performed for three different load and boundary conditions. At the end of the work, conclusions are drawn on the basis of the tests carried out.