The paper presents the results of an experimental and numerical study of hydrodynamics and heat transfer in a pebble bed with internal volumetric heat release. An experimental setup with two test sections was designed to investigate the hydrodynamics and heat transfer at the axial and radial flow of a single-phase coolant. The pebble bed was set from 2.0 mm diameter sphere made of AISI 420 steel. The internal heat release model in the pebble bed is provided by high-frequency induction heating, whereby the thermal power of the high-frequency installation is 20 kW. The experiments were carried out in the range of mass flow rates of 0.1 - 0.6 kg/s. To investigate the axial flow of the coolant at the work site, the pebbles were placed in a vertical cylindrical tube and held by perforated plates from the top and from the bottom. Data were obtained for pressure drop; the hydraulic resistance coefficients of the pebbles and the heat transfer coefficients were determined. For the first time, the hydraulic resistance coefficient of a perforated plate with an adjacent layer of pebbles was recorded. The working section for the study of transverse flow in the coolant simulates the fuel assembly of a nuclear reactor with microfuge. Pebbles are placed between the inner and outer perforated covers. Transverse coolant flow is achieved to minimize pressure losses. The inner cover is cone-shaped and is the dispensing manifold for the coolant. The conical shape of the cover provides a uniform flow rate of the cooling liquid along the length of the test section. The pressure drop and temperature distribution in the pebbles were recorded.