Efficiency and safety were considered as the one of the important factors in the nuclear power plant. For this reason, many researchers have studied the heat transfer phenomena of the fuel rod in view of the coating. Due to these nanoparticles, the heat transfer performance of the fuel rod with a coated surface is improved.
The high temperature of the cladding surface attracts impurities and chemical additives into the reactor coolant that are deposited on the fuel rod surface in the process. Macroscopic observations of the inner surface of the test section after the quenching experiments: (a) water, (b) SiC/water nanofluid and (c) GO/water nanofluid. SEM observations of the inner surface of the test section after the quenching experiments:. a) water, (b) SiC/water nanofluid and (c) GO/water nanofluid.
SEM-EDS results of the inner surface of the test section after SiC/water nanofluid quenching experiments. SEM-EDS results of the inner surface of the test section after GO/water nanofluid quenching experiments.
Introduction
Background
Fuel assemblies removed from an AOA core exhibit a thick porous deposit layer of crude oil on the fuel-coated surface. The deposit layer was induced by precipitation reactions of both boron species and crude oil during supercooled core boiling. To solve the AOA problems, EPRI has therefore developed a fuel cleaning technology that uses ultrasonic cavitation.
The injection of soluble zinc addition to the reactor coolant was used for the purpose of radiation field reduction, general corrosion control.
Objectives
Literature Study
- General Characteristics of Nanofluid
- Reflooding
- Mechanism of Entrainment
- Characteristic of crud
- Characteristic of Cavitation
They stated that a significantly large heat transfer coefficient is obtained in a wide range of the wall superheat compared to that of the bare Pt wires cooled by the water and the nanofluids during quenching of the Si - and SiC nanoparticle-coated Pt wires. ECCS is one of the safety systems in the NPP (Nuclear Power Plant) designed to automatically maintain the system. Therefore, phase change of water interaction with heated wall is important as part of the research of the ECCS.
It is a function of the wall properties, initial wall temperature and coolant inlet temperature and mass flux. Before cooling the quench front through wetting with coolant, entrainment is generated, which occurs during refilling due to the interaction between coolant and heated wall downwards. It indicates that the increase in species concentrations towards the bottom of the crud causes an increase in the saturation temperature, and because the solubility of LiBO2 decreases with increasing temperature, it precipitates.
And the added results show how the temperature at the bottom of the raw deposits varies with the thickness of the rough and the boron concentration of the bulk water, as shown in Figure 4. The effects of the throat velocity and the cavitation number σ (referred to the pressure in the flow of bottom and throat velocity ) were studied on the erosion rate (MDPR: Mean Depth of Penetration Rate). 29) analyzed the effect of nanobubbles on foam flotation. In this study, a model of erosion damage and cleaning efficiency of cavitation jets and conventional cleaning is presented.
Temperature at the bottom of the crude oil for different crude oil thicknesses, at different boron concentrations in the bulk water (26).
Experiments of Reflooding on Long Vertical Tube
Preparation of Nanofluid
As the pH changes from the IEP, the absolute value of the zeta potential of the particle surface increases so that the interaction between particles due to the existence of the electric double layer (EDL) becomes sufficient to prevent the attraction and collision between particles caused by Brownian. movement.
Reflood Test
Results and Discussion
Comparisons of Quenching Performance
Analysis of Specimens
The reasons for the improvement in cooling performance were investigated by macroscopic observation, SEM, contact angles and SEM EDS of the inner surface of the test section in the same way as for nanofluids. Macroscopic observations show the deposition of SiC nanoparticles on the inner surface of the test section. SEM observations show in more detail the inner surface of the test section after quenching experiments with water and SiC/water nanofluid.
And Figure 23 shows the SEM-EDS results of the inner surface of the test section after the GO/water nanofluid quenching experiments. To confirm the improved wettability of the liquid film on the heating surface, the contact angle is examined as shown in Figure 24. The contact angles in the inner surface of the test section after the quenching experiment with water, SiC/water nanofluid and GO/water nanofluid are.
The contact angles in the inner surface of the test section after reflow experiment with SiC/water nanofluid and GO/water nanofluid were the smaller than those of water.
Experiments of Hydrodynamic Cavitation
Cavitation Simulation Facility
Preparation of Coated Specimens
Measurements of Shock Pressure
Results and Discussion
CFD analysis
Image of Bubble Flow
Pressure Film
Sample Test
This is considered one of the strong candidates to function as a fuel rod cladding material in advanced and fusion reactors. If used as a floating material in the coolant, it can work to reduce and repair the damage to the fuel caused by the nuclear accident. And if we consider SiC-coated samples, the removal of the coated surface by cavitation can be attached to the weight loss caused by the erosion effect.
So, selection of SiC nanoparticle can be attributed to ensure the safety in the nuclear power plant. These experiments are firstly researched using the SiC/water and GO/water nanofluids on the reflow system in the long vertical tube. In addition, this test can attribute the verification of resistance of cavitation on the SiC cladding.
The present work was carried out to investigate the effect of nanofluids on heat transfer in reflooding in a long vertical tube. The reason for the improvement in cooling performance after quenching experiments using nanofluids was investigated by macroscopic observation, SEM, contact angles and SEM-EDS of the inner surface of the test section. At certain distances from the end of the opening, most of the bubbles cannot be seen and form around the opening.
It looks like the result of shock pressure when the bubble collapses through eddy flow. Cavitation experiment using the SiC coated samples on each cavitation number is useful to analyze the damage of SiC cladding when exposed to cavitation. you, S.; Kim, J.; Kim, K., Effect of nanoparticles on critical heat flux of water in pool boiling heat transfer.
C.; Heung Chang, S., Boiling heat transfer and phenomena of Al2O3-water nanofluids from a plain surface in a pool. In Film boiling heat transfer on a high temperature sphere in nanofluid, Proceeding of the ASME Heat Transfer/Fluids Engineering Summer Conference: Volume 4, 2004; pp. 469-476. Kim, H.; DeWitt, G.; McCrell, T.; Buongiorno, J.; Hu, L., On quenching of steel and zircaloy spheres in aqueous nanofluids with alumina, silica and diamond nanoparticles.
Bolukbasi, A.; Ciloglu, D., Vertical cylinder pool wave heat transfer characteristics quenched by SiO 2 water nanofluids.Film boiling inside vertical tubes with upflow of low-quality liquid; Cambridge, Mass.: Deptt.
Summary & Conclusions
