Anhar Riza Antariksawan

Simulation of Heat Flux Effect in Straight Heat Pipe as Passive Residual Heat Removal System in Light Water Reactor Using RELAP5 Mod 3.2

Heat pipe is considered being used as a passive system to remove residual heat that generated from reactor core when incident occur or from spent fuel pool. The present research is aimed to studying the characteristics of straight heat pipe as passive residual heat removal system. As an initial step, a numerical simulation was conducted to simulate the best experimental design set up being prepared for the next step of the research. The objective is to get the thermal hydraulic characteristic due to variation of heat flux of heat source. The thermal hydraulic RELAP5 MOD 3.2 code is used to simulate and analyze the straight heat pipe characteristics. Variations of heat flux are 1567 Watt/m2, 3134 Watt/m2, 4701 Watt/m2, 6269 Watt/m2, and 7837 Watt/m2. Water as working fluid is heated on evaporation section with filling ratio 60%. Environmental air with variation 5 m/s and 10 m/s of velocity are used as external cooler. Straight heat pipe used in the simulation is wickless with 0.1 m of diameter and 6 m of length. The results show that higher heat flux given to the evaporator section will lead to more rapid heat transfer and achievement of steady state condition. The increasing of heat flux leads to an increase of evaporation of the working fluid and of pressure built in the heat pipe affecting higher saturation temperature of working fluid. Heat flux loading must consider the velocity of air as heat removal in the condenser to prevent dry out phenomenon in the evaporator. Based on the results, given the experimental set-up, the optimum range of experimental parameters could be determined.

Preliminary investigation of natural circulation stability in FASSIP-01 experimental facility using RELAP5 code

Natural circulation has an important role in the safety system of a nuclear reactor. It is part of passive system, which is operated without any external prime mover. The behavior of natural circulation shall be known to be effectively incorporated in the safety system of a nuclear reactor. This paper describes the preliminary results of the study on natural circulation conducted at a vertical rectangular experimental facility FASSIP-01. The RELAP5 code is used to simulate the experiment. The goal is to study the validity of the RELAP 5 model to analyze the natural circulation in FASSIP-01. The simulation could provide a reasonable good results describing the natural circulation established in the rectangular loop of FASSIP-01. However, there are still discrepancies with the experimental results, especially with regard to mass flow rate and temperature distribution in the loop. The model needs be improved and further comprehensive data from experiments are necessitated for better validation, as well.Natural circulation has an important role in the safety system of a nuclear reactor. It is part of passive system, which is operated without any external prime mover. The behavior of natural circulation shall be known to be effectively incorporated in the safety system of a nuclear reactor. This paper describes the preliminary results of the study on natural circulation conducted at a vertical rectangular experimental facility FASSIP-01. The RELAP5 code is used to simulate the experiment. The goal is to study the validity of the RELAP 5 model to analyze the natural circulation in FASSIP-01. The simulation could provide a reasonable good results describing the natural circulation established in the rectangular loop of FASSIP-01. However, there are still discrepancies with the experimental results, especially with regard to mass flow rate and temperature distribution in the loop. The model needs be improved and further comprehensive data from experiments are necessitated for better validation, as well.

Estimation of natural circulation flow based on temperature in the FASSIP-02 large-scale test loop facility

In the future, the use of passive cooling system without electrical power input become highly considered to be implemented in the design of nuclear reactor safety system. Moreover, the lessons learned from the Fukushima-Daiichi accident encourage the incorporation of such passive cooling system. The passive safety cooling system is aimed to cope with both design bases as well as severe accidents. The natural circulation is one example parameter of the passive cooling system features being widely considered. However, some of the parameters involving in natural circulation are still being investigated, in particular the problem of flow instability. BATAN is designing a large-scale test loop facility, named FASSIP-02 loop, with a height of 11 meters between a heat source and a cooling source. The FASSIP-02 loop is designed to simulate the residual heat in the reference reactor. To ensure the validity of the design prior to the construction, it is necessary to make an analytical calculation using some correlations to estimate the natural circulation flow rate. The calculation method is performed by using the derived two principle correlations of the buoyancy force in the heating section and the gravitational force on the cooling section. The water temperatures in the heating section are varied at 50°C, 60°C, 70°C, 80°C and 90°C with the water temperature in the cooling tank pool are varied at 10°C, 20°C, 30°C, 40°C and 50°C. The calculation results can estimate the water temperature and volume are required. In addition, it could be used to determine the experimental matrix that is based on the FASSIP-02 loop design.

Numerical study on natural circulation characteristics in FASSIP-02 experimental facility using RELAP5 code

As in many other energy generating system, in the nuclear power plant, the use of natural circulation principle for the safety system is increasingly considered. The natural circulation could play an important role in providing emergency cooling of the nuclear reactor. The reliability of the use of natural circulation in the nuclear power plant should be demonstrated in order to assure the level of its safety. FASSIP-02 is a large scale test facility to study the natural circulation in the safety system of a nuclear power plant. To study the characteristics of the natural circulation and to help validating the design of FASSIP-02, a numerical study using RELAP5 code is undertaken. Based on the existing design of FASSIP-02, the numerical simulation is done with two variables, i.e. the heat flux and the pipe diameter. The effect of heat transfer surface area for dissipating the heat is also studied. The results show the natural circulation established in the FASSIP-02. The characteristics of the natural circulation with the values of several important parameters such as temperature, mass flow rate and pressure in the loop are obtained. The RELAP 5 calculations have provided the results that could be used to support the design and future operation of FASSIP-02.

Preliminary investigation of wickless-heat pipe as passive cooling system in emergency cooling tank

To improve the thermal safety of a nuclear power plant, a wickless-heat pipe is proposed as a passive cooling system on an emergency cooling tank. Heat pipe will keep the water in the emergency cooling tank on normal operating temperature. The objective of this preliminary research is to investigate the characteristics of the wickless-heat pipe. RELAP/SCDAPSIM/MOD3.4 thermal-hydraulic code was used to analyze the characteristics of the wickless-heat pipe. The simulation results will be used as a basis for designing the future experimental investigations of the proposed wickless-heat pipe. The influence of the hot water temperature in the emergency cooling tank and the mass flow rate of coolant on the water jacket were investigated. The hot water temperature in the emergency cooling tank was varied, i.e. 60, 70, and 80°C. The mass flow rate of condenser coolant in the water jacket was varied, i.e. 2, 4, and 8 L/min. The initial pressure of the heat pipe was -74 cm Hg. De-mineralized water, which serves as heat pipe working fluid, was charged with filling ratio of 80%. The working fluid in the heat pipe can circulate naturally in stable condition if cooling water could absorb the latent heat in condenser. The simulation results showed that for constant hot water temperature, the increasing of condenser coolant volumetric flow rate will decrease the temperature of evaporator and condenser. While for constant condenser coolant volumetric flow rate, the increasing of hot water temperature will increase the temperature of evaporator and condenser.To improve the thermal safety of a nuclear power plant, a wickless-heat pipe is proposed as a passive cooling system on an emergency cooling tank. Heat pipe will keep the water in the emergency cooling tank on normal operating temperature. The objective of this preliminary research is to investigate the characteristics of the wickless-heat pipe. RELAP/SCDAPSIM/MOD3.4 thermal-hydraulic code was used to analyze the characteristics of the wickless-heat pipe. The simulation results will be used as a basis for designing the future experimental investigations of the proposed wickless-heat pipe. The influence of the hot water temperature in the emergency cooling tank and the mass flow rate of coolant on the water jacket were investigated. The hot water temperature in the emergency cooling tank was varied, i.e. 60, 70, and 80°C. The mass flow rate of condenser coolant in the water jacket was varied, i.e. 2, 4, and 8 L/min. The initial pressure of the heat pipe was -74 cm Hg. De-mineralized water, which serves as ...

Experimental Study on Counter Current Flow Limitation Based on Variation of Gap Size in Narrow Rectangular Channel during Quenching Process

The Effect of gap size to counter current flow limitation (CCFL) in vertical rectangular channel was studied in this paper. Experiment was conducted by using two vertical plate with 1 mm, 2 mm, and 3 mm narrow gap. The initial temperature of plate was decided at 600oC. Flow rate and temperature of cooling water were controlled about 0.09 L/s and 90oC respectively. Non-dimensional superficial velocity for water is 0.05-0.09 and non-dimensional superficial velocity for vapor is 3.20-3.2. The result shows that the existence of CCFL in the vertical rectangular narrow channels. A new correlation for CCFL base on Wallis has been proposed.