• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.21 no.4
• /
• pp.439-450
• /
• 2023

In this study, the impact load resulting from collision with the fuel rods of surrogate spent nuclear fuel (SNF) assemblies was measured during a rolling test based on an analysis of the data from surrogate SNF-loaded sea transportation tests. Unfortunately, during the sea transportation tests, excessive rolling motion occurred on the ship during the test, causing the assemblies to slip and collide with the canister. Hence, we designed and conducted a separate test to simulate rolling in sea transportation to determine whether such impact loads can occur under normal conditions of SNF transport, with the test conditions for the fuel assembly to slide within the basket experimentally determined. Rolling tests were conducted while varying the rolling angle and frequency to determine the angles and frequencies at which the assemblies experienced slippage. The test results show that slippage of SNF assemblies can occur at angles of approximately 14° or greater because of rolling motion, which can generate impact loads. However, this result exceeds the conditions under which a vessel can depart for coastal navigation, thus deviating from the normal conditions required for SNF transport. Consequently, it is not necessary to consider such loads when evaluating the integrity of SNFs under normal transportation conditions.

• Nuclear Engineering and Technology
• /
• v.52 no.3
• /
• pp.520-529
• /
• 2020

Experimental investigations were attempted to simultaneously observe the vapor behaviors and critical heat flux under static and rolling conditions. From visualization results, vapor initiated, grew, and detached individually in a vertical direction from the static heated surfaces (at 10, 20, and 30°). While under rolling motion, initiated vapor grew, and interacted with each other, resulting in forming a wider dry spot on the heated surface. Also, it was observed that the vapor drifted upward and stayed on the heated surface longer compared to under static condition. The faster the platform rolls, the longer the vapor stay on the heated surface, significantly decreasing the CHF. On the other hand, as the platform rolls slower (at high rolling period), CHF increases. CHF was decreased with increasing maximum rolling amplitude and inclination angle under both conditions (static and rolling). CHF under rolling conditions was noticed to be lower than under static condition except at maximum rolling amplitude of 10°. The bubble departure frequency at a maximum rolling amplitude of 10° was the highest among all of rolling amplitudes, thereby enhancing the CHF. These results indicate that rolling motion significantly affects vapor behaviors and CHF.

• Journal of Welding and Joining
• /
• v.34 no.6
• /
• pp.20-27
• /
• 2016

This study deals with the proper conditions of the trail rolling method (TRM) for the prevention of the buckling welding distortion at the AA5083 GMA butt weldment. For it, the effect of the working conditions of TRM including the rolling depth and the rolling distance between the welding torch and the roller on the longitudinal welding shrinkage force of the weldment was evaluated by using 3 dimensional thermo-mechanical FE analyses. The longitudinal welding shrinkage force inducing the buckling welding distortion at the GMA butt weldment was mitigated with an increase in the rolling depth and the rolling distance between the welding torch and the roller. Based on the results, the proper conditions of trail rolling method were established to reduce the longitudinal welding shrinkage force of the GMA butt weldment to below the critical value corresponding to the bucking distortion.

• Transactions of Materials Processing
• /
• v.15 no.7 s.88
• /
• pp.479-484
• /
• 2006

The evolution of strain states and textures during rolling with various conditions was investigated by finite element method (FEM) simulations and measurements of rolling textures. Symmetrical rolling with a high friction gives rise to a strong variation of shear strains in rolled sample leading to the formation of texture gradients throughout the thickness layers. A small variation of shear strains during rolling with a well lubrication condition leads to the formation of a fairly homogeneous rolling texture throughout the sheet thickness. During asymmetrical rolling, a proper control of rolling parameters provides the evolution of a fairly homogeneous shear texture throughout the whole sheet thickness.

• Journal of the Korean Society for Precision Engineering
• /
• v.10 no.4
• /
• pp.128-134
• /
• 1993

Work roll wear in the cold rolling of mild steel strip is strongly affected by rolling materials, rolling conditions and lubrication. The tests were performed to find the effects of rolling materials under the same lubrication conditions. The obtained results are as follfws; 1) The decrease in surface roughness of work roll is more rapid in that case of continuously cast A1-killed steel strip than ingot cast steel strip. In rolling of continuously cast A1-killed steel strip, worn powder rich in A1$\_$2/O$\_$3/sticks to the work roll surface, and so it makes the mirror surface of work roll accelerate. 2) Amount of work roll wear is small in rolling of continuously cast A1-killed strip. 3) In rolling of continously cast A1-killed steel strip, it is necessary to put up the intial surface roughness of work roll in order to prevent work roll slip.

• Tribology and Lubricants
• /
• v.13 no.2
• /
• pp.74-81
• /
• 1997

The purpose of this study is to develop a cold rolling oil with lubricity and mill cleanness property under the rolling conditions of high reduction ratio and high rolling speed. Six kinds of oil samples were blended. Evaluation of lubricity and anti-seizuro property of the samples were carried out with a laboratory scale rolling mill, where the contact conditions between work roll and strip are very close to actual cold rolling mill. Laboratory evaluation for dispersion, contamination, anti-oil stain property and residual carbon, etc. were carried out with several testers such as longterm circulation tester, Coulter counter and Conradson tester. A new high speed cold rolling oil with good lubricity and mill cleanness property was developed compared with the previously developed rolling oil.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1997.04a
• /
• pp.1-5
• /
• 1997

The plane surface rolling, one of the plastic working process, good surface condition due to increase of surface roughness and hardness. It is well known that mechanism of surface rolling depends upon rolling conditions such as rolling speed, contact pressure, step length of rolling, the shape of roller and mechanical properties of material. In this study, the optimal value of the above parameter on the surface roughness were investigated by using the rolling tool with NACHI 6000ZZ ball bearing outer races on machine structure carbon steel[SM45C]

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2006.05a
• /
• pp.63-66
• /
• 2006

The effect of warm rolling under various conditions on the microstructure and mechanical property was investigated using an AZ31 Mg alloy sheet. Several processing parameters such as initial thickness, thickness reduction by a single pass rolling, rolling temperature, roll speed, and roll temperature were varied to elicit an optimum condition for the warm rolling process of AZ31 Mg alloy. Microstructure and mechanical properties were measured for specimens subjected to rolling experiments of various conditions. Warm rolling of 30% thickness reduction per pass was possible without any side-crack at temperatures as low as $200^{\circ}C$ under the roll speed of 30 m/min. The initial microstructure before rolling was the mixed one consisting of partially recrystallized and cast structures. Grain refinement was found to occur actively during the warm rolling, producing a very fine grain size of 7 mm after 50% reduction in single pass rolling at $200^{\circ}C$. Yield strength of 204MPa, tensile strength of 330MPa and uniform elongation of 32% have been obtained in warm rolled sheets.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1999.10a
• /
• pp.74-80
• /
• 1999

Work roll wear in the cold rolling of mild steel strip is strongly affected by rolling materials, rolling conditions such as roll arrangement in the cold rolling mill and lubrication. The tests were performed to find the effects of roll arrangement n the cold rolling mill on the work roll wear under the same lubricating conditions. The obtained results are as follows:If the distance of cold rolling is about 60km, the surface roughness of its was reduced by half(Ra 0.49${\mu}{\textrm}{m}$) and Pc(peak count) also was decreased to 60 ea/cm.It is easier for CC(Continuous casting) to make a slip on rolling than IC(Ingot casting). It is due to surface mirror in which first residual product appears and iron powder included Al2O3 is sticked. Because bending degree of 4Hi-rolling mill is higher than 6Hi-rolling mill, the first surface mirror was occurred to its center-point which is loaded strongly. 6Hi-rolling mill shape-controlled by intermediate roll doesn't need the initial crown to work roll. Therefore, fatigue and wear would appear a little bit.

• Nuclear Engineering and Technology
• /
• v.53 no.6
• /
• pp.1810-1820
• /
• 2021

Study of single bubble behavior under rolling motions can prove useful for fundamental understanding of flow field inside the modern small modular nuclear reactors. The objective of the present study is to simulate the influence of rolling conditions on single rising bubble in a liquid using multiphase Moving Particle Semi-implicit (MPS) method. Rolling force term was added to 2D Navier-Stokes equations and a computer program was written using C language employing OpenACC to port the code to GPU. Computational results obtained were found to be in good agreement with the results available in literature. The impact of rolling parameters on trajectory and velocity of the rising bubble has been studied. It has been found that bubble rise velocity increases with rolling amplitude due to modification of flow field around the bubble. It has also been concluded that the oscillations of free surface, caused by rolling, influence the bubble trajectory. Furthermore, it has been discovered that smaller vessel width reduces the impact of rolling motions on the rising bubble. The effect of liquid viscosity on bubble rising under rolling was also investigated and it was found that effects of rolling became more pronounced with the increase of liquid viscosity.