Two experimental loops for operation in research reactor LVR-15 in ÚJV Řež are recently under preparation: High Temperature Helium Loop (HTHL) and SuperCritical Water Loop (SCWL). Pure helium will be used as working medium in HTHL and its main physical parameters are: operating pressure 7MPa, max. temperature in the test section 900°C and flow rate 36kg/h. HTHL will include helium purification system, system for dosage of impurities (e.g. CO2, H2, H2O, O2, N2 etc.) and helium sampling. Helium purification experiments and testing of materials in simulated HTR conditions will take place in HTHL in the future. Main parameters of the SCWL are 25MPa, max. temperature in the test section 600°C, flow rate max. 200kg/h. SCWL will be used for corrosion tests of candidate materials, studies of water radiolysis at supercritical conditions and for testing of water chemistry suitable for operation. Both loops possess an irradiation channel with quite complicated internals design, whose complexity is imposed by current constraints on constructional materials of nuclear experimental devices, which limit the choice and maximum surface temperature of material of construction to 500°C for austenitic stainless steel. The working temperature will thus be attained only in a restricted volume of the test section. The channel internals will be briefly described. The mentioned loops will represent novel experimental devices, whose objective is to gain and extend knowledge on materials and environment performance under the influence of radiation.