tip leakage loss introduces major part of losses of the rotor in axial gas turbines. therefore, the rotor blade tip has a considerable effect on rotor efficiency. to understand the flow physics of the rotor tip leakage, we solve the flow field for different tip platforms (passive flow control) and by considering coolant tip injection (active flow control). various blade tip configurations such ...

Since the counter current flow limitation (CCFL) of two-phase has an important influence on safety analysis reactor, it is also great significance to study some characteristics and pattern transitions flow. In order explore influencing factors in hot leg under condition Loss Coolant Accident, this research, using RELAP5 simulation calculation, analyzed effect lengths path leg, shapes upper outl...

Pebble Bed Reactors could allow nuclear plants to support the goal of reducing global climate change in an energy hungry world. They are small, modular, inherently safe, use a demonstrated nuclear technology and can be competitive with fossil fuels. Pebble bed reactors are helium cooled reactors that use small tennis ball size fuel balls consisting of only 9 grams of uranium per pebble to provi...

In this paper we propose and discuss variance reduction techniques for the estimation of quantiles of the output of a complex model with random input parameters. These techniques are based on the use of a reduced model, such as a metamodel or a response surface. The reduced model can be used as a control variate; or a rejection method can be implemented to sample the realizations of the input p...

Fuel rod analysis program transient (FRAPTRAN) code was used to study the fuel rod performance during a postulated large break loss of coolant accident (LBLOCA) in Maanshan nuclear power plant (NPP). Previous transient results from thermal hydraulic code, TRACE, with the same LBLOCA scenario, were used as input boundary conditions for FRAPTRAN. The simulation results showed that the peak claddi...

A tungsten oxidation mechanism map is developed to clarify literature confusion about the dominant kinetic regime and enable improved predictions in extreme environments. Thermogravimetry data systematically extracted from 14 papers range 600–1600 °C treated as three distinct regimes: parabolic oxidation, linear sublimation. constructed that shows metal recession thickness contours for each tim...

During the almost seven decades of use nuclear fission for electric energy production two major accidents took place, i.e., 1986 Chernobyl accident and 2011 Fukushima one. They were caused by reactor power-surge loss-of-coolant, respectively. Both occurred during hot power shutdown had identical root causes, poor safety culture management in industry state authorities. A brief comparison facili...

Probabilistic safety assessment (PSA) which plays a crucial role in risk evaluation is a quantitative approach intended to demonstrate how a nuclear reactor meets the safety margins as part of the licensing process. Despite PSA merits, some shortcomings associated with the final results exist. Conventional PSA uses crisp values to represent the failure probabilities of basic events. This causes...