Reflooding tests on WWER fuel subassembly models

The paper presents the results of experimental and calculational studies of reflooding phenomenon in a WWER fuel subassembly model consisting of 7 rods. A description of equipment used and test procedures is given. Electrically heated rods (indirect heating) of a capacity of 10 kW with a stepwise axial power generation are employed as heater rods. Each heater rod is provided with 6 surface thermocouples installed on 3-6 levels. Data collection and processing is implemented by a fast-response system based on PC-486 compatible IBM with an input-output frequency of 90 kHz. In the course of tests, a study was performed on the effect of the initial power generation, pressure, flooding rate, inlet coolant temperature, the number and position of non-heated rods, and the perforated plate at the test section exit on the rate of wetting front and the thermal behaviour of heater rods. The experimental results obtained were compared with the calculations performed using the RELAP5/Mod3 Code. (author)