Design Implementation and Parallel Operation of High-Current High-Power Multipulse Converters Feeding Nuclear Fuel Simulators

Nuclear reactors are designed to maintain a chain reaction producing a steady flow of neutrons generated by fission of heavy nuclei, such as uranium. They produce thermal energy, which is converted into mechanical energy and ultimately into electrical energy feeding to a grid network. In a nuclear reactor, fuel undergoes various power/temperature transients during normal and off-normal situations. One needs to simulate these transients in experimental facilities for performing variety of reactor engineering and safety related tasks. The facility consists of scaled thermal hydraulic test setup comprising process equipment, instrumented nuclear fuel channel simulator, and high current converters for feeding power equivalent to fission power to those simulators to handle the transients safely in controlled manner. The experimental results are used to generate database of various vital nuclear reactor process parameters under all types of operational transients and off-normal conditions that can be compared with predictions from computer codes thus validating ever-evolving and advanced software. Besides, simulation of severe accidental conditions of nuclear reactor in facility is also necessary for evaluation of thermal hydraulic design safety margin. A low-resistance fuel simulator of identical geometry with power scaling is directly heated by high dc current to simulate fission power for generating experimental database. The converters have capability to generate power/temperature transients for simulating nuclear reactor conditions. This article presents design, functional description, specifications, simulation, hardware implementation of 10 kA, 12-pulse, thyristorized converters powering fuel simulators. The successful implementation of parallel operation of four converters feeding 27 kA current is described in this article.