The cooling reactor in Fukushima Nuclear Power Plant (NPP), Japan, was not working shortly after the massive earthquake some time ago. The malfunction reduced the cooling of nuclear reactor (small break loss of coolant accident, SBLOCA) in short time.
According to Mahmudin, SBLOCA can cause temperature and gas pressure in core reactor very high. The pressure and temperature might lead to an explosion. "To understand how the accident could happen, a deeper study of the phenomenon of flooding needs to be done," Mahmudin said in Department of Mechanical and Industrial Engineering UGM on Tuesday (31/1) during his open doctoral examination.
Accompanied by promoter Ir. Samsul Kamal, M.Sc., Ph.D. and co-promoters, Prof. Dr. Ir. Indarto, DEA, and Ir. Purnomo, MSME., Ph.D, Mahmudin defended his dissertation "Characteristics of Hydrodynamics and Heat Transfer in the Phenomenon of Flooding in Vertical Heat Pipe". He said that flooding phenomenon is Counter-Current Flow Limitation (CCFL) which occurs when some of the water flows upward in the direction of air flow in a pipe. "Therefore, the failure of cooling in reactor core can increase wall surface temperature suddenly. This condition makes the formation of vapor exceed the permitted threshold," said the lecturer of Department of Engineering, Faculty of Engineering, University of Muslim Indonesia, Makassar.
Therefore, using the calibration scheme of the temperature and film pressure censor, Mahmudin in his research wanted to find flow pattern of annular flow and churn flow. In addition, it also observed water droplets, droplets, ring-type waves, single wave and local bridging. "The results are expected to provide simpler insight into the flooding phenomenon. It is also expected to be applied in some power plant industries, especially for industries that use the upright evaporator and condenser," he said.
Mahmudin added that when flooding is observed, there is sudden rise in temperature and pressure. It is similar to the phenomenon occurred at Fukushima nuclear reactor. "Therefore, this research model could be developed at high temperature to meet the real criteria," Mahmudin added.