• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.345-350
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• 2000

The heat produced by the fission in the fuel of HANARO, 30 MW research reactor, is transferred from the primary cooling water to the secondary cooling water through heat exchangers, and the heat absorbed by the secondary cooling water is released into the atmosphere by the 33 MW cooling tower which is a mechanical induced draft and counter flow type. If the outlet temperature of cooling tower exceeds 33 of due to the loss of the cooling tower performance under reactor operation above $50\%$ of the full power, the reactor power should be reduced to half of the full power for safe operation. Therefore, the cooling capability of cooling tower should be maintained for the reactor to be normally operated. To predict the capability of cooling tower for full power reactor operation of 30 MW, the performance test of cooling tower was done at the reactor present power of 24 MW and the capability was respectively evaluated by characteristics and performance curves methods in accordance with the Code of Cooling Tower Institute of U.S.A. to confirm the reliability of evaluation. As a result, it was confirmed, through the results of each evaluation, that the cooling capability of cooling tower meets the design required heat load. Also, the equations of the performance and the characteristics curves of the cooling tower, based on the collected data during this performance test, was obtained for developing the calculation program to predict the cooling capability during reactor operation.

• Transactions of Materials Processing
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• v.25 no.4
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• pp.242-247
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• 2016

CFD simulation with FlowVision^® is used to evaluate the capability of cooling channel in hot press forming dies. Two different types of cooling channels, dry drilled and pocket types are considered for comparison. Two different approaches for simulating cooling channel are considered. One is single-phase velocity calculation for coolant only and the other is multiphase thermal and velocity calculation for die, blank and coolant all together. Both approaches show better cooling performance in pocket type cooling channel. Also both approaches show their own effectiveness in designing cooling channel of hot press forming dies.

• Journal of Energy Engineering
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• v.20 no.4
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• pp.259-266
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• 2011

Following the reactor shutdown, the reactor shutdown cooling system must be designed to supply the coolant sufficiently not only to remove the decay heat but to maintain the adequate cooling rate to protect the reactor equipments. In this study, KDESCENT code for the light water reactor and SOPHT, SDCS codes for the heavy water reactor were compared and analyzed to investigate the cooling capability during the shutdown cooling process. The shutdown cooling system design requirements were satisfied during cooling process for both the SDCP and the HTP modes and the design cooling rate of $2.8^{\circ}C/min$ or below was maintained using the SDC heat exchangers. This study shows that the shutdown cooling system in the Wolsong 2, 3, 4 reactors provides sufficient cooling to maintain the nuclear fuel integrity by removing the decay heat of the nuclear fission product.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2714-2719
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• 2007

HANARO, an open-tank-in-pool type research reactor of 30 MWth power in Korea, has been operating normally since its initial criticality in February, 1995. For the last about ten years, A cooling tower of a secondary cooling system has been operated normally in HANARO. Last year, the cooling tower has been overhauled for preservative maintenance including fills, eliminators, wood support, water distribution system, motors, driving shafts, gear reducers, basements, blades and etc. This paper describes the results of the overhaul. As results, it is confirmed that the cooling tower maintains a good operability through a filed test. And a cooling capability will be tested when a wet bulb temperature is maintained about 28 $^{\circ}C$ in summer and the reactor is operated with the full power.

• Nuclear Engineering and Technology
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• v.31 no.5
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• pp.476-485
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• 1999

In order to evaluate the gravity-injection capability to maintain core cooling after a loss-of-shutdown-cooling event during shutdown operation, the plant conditions of the Yong Gwang Units 3&4 were reviewed. The six cases of possible gravity-injection paths from the refueling water tank (RWT) were identified and the thermal-hydraulic analyses were performed using the RELAP5/MOD3.2 code. The core cooling capability was significantly dependent on the gravity-injection path, the RCS opening, and the injection rate. In the cases with the pressurizer manway opening higher than the RWT water level, the coolant was held up in the pressurizer and the system pressure continued increasing after gravity-injection. The gravity injection eventually stopped due to the high system pressure and the core was uncovered. In the cases with the injection path and opening on the same leg side, the core cooling was dependent on whether the water injected from the RWT passed the core region or not. However, in the cases with the injection path and opening on the different leg side, the system was well depressurized after gravity-injection and the core boiling was successfully prevented for a long-term transient. In addition, from the sensitivity study on the gravity-injection flow rate, it was found that about 54 kg/s of injection rate was required to maintain the core cooling and the core cooling could be provided for about 10.6 hours after event with that injection rate from the RWT. Those analysis results would provide useful information to operators coping with the event.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.1
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• pp.36-42
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• 2007

The latest cars give much importance in the role of HVAC system that controls the environment of the area for passengers more than just basic capability In this study, we drew the automobile interior as three dimension and arranged a method of numerical analysis on HVAC environment in the automobile interior displaying air current distribution and temperature distribution through simulation of the automobile interior on the ventilation volume and outlet area, The aim of this study is to develop the estimated method for HVAC environment in the automobile interior. Results of numerical analysis, to cool automobile interior needs more considerations if thinking cheerful surroundings of automobile interior air but the more magnitude of outlet is small, the more cooling capability is excellent and realistic countermeasures about a realistic geometry and boundary condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.455-456
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• 2007

• Nuclear Engineering and Technology
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• v.38 no.1
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• pp.45-60
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• 2006

Presently, the VHTGR (Very High Temperature Gas-cooled Reactor) is considered the most attractive candidate for a GEN-IV reactor to produce hydrogen, which will be a key resource for future energy production. A new concept for a reactor cavity cooling system (RCCS), a critical safety feature in the VHTGR, is proposed in the present study. The proposed RCCS consists of passive water pool and active air cooling systems. These are employed to overcome the poor cooling capability of the air-cooled RCCS and the complex cavity structures of the water-cooled RCCS. In order to estimate the licensibility of the proposed design, its performance and integrity were tested experimentally with a reduced-scale mock-up facility, as well as with a separate-effect test facility (SET) for the 1/4 water pool of the RCCS-SNU to examine the heat transfer and pressure drop and code capability. This paper presents the test results for SET and validation of MARS-GCR, a system code for the safety analysis of a HTGR. In addition, CFX5.7, a computational fluid dynamics code, was also used for the code-to-code benchmark of MARS-GCR. From the present experimental and numerical studies, the efficacy of MARS-GCR in application to determining the optimal design of complicated systems such as a RCCS and evaluation of their feasibility has been validated.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2438-2446
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• 2023

To cool down a nuclear reactor core and prevent the fuel damage without a pump-driven active component during any anticipated accident, the passive emergency core cooling system (PECCS) was designed and adopted in an advanced light water reactor, i-POWER. In this study, for a validation of the cooling capability of PECCS, thermal-hydraulic integral effect tests were performed with the ATLAS facility by simulating intermediate and small break loss-of-coolant accidents (IBLOCA and SBLOCA). The test result showed that PECCS could effectively depressurize the reactor coolant system by supplying the safety injection water from the safety injection tanks (SITs). The result pointed out that the safety injection from IRWST should have been activated earlier to inhibit the excessive core heat-up. The sequence of the PECCS injection and the major thermal hydraulic transient during the SBLOCA transient was similar to the result of the IBLOCA test with the equivalent PECCS condition. The test data can be used to evaluate the capability of thermal hydraulic safety analysis codes in predicting IBLOCA and SBLOCA transients under an operation of passive safety system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.121-128
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• 2012

The optimization of cooling system parameters for designing injection mold is very important to acquire the highest part quality. In this paper, the integration of computer simulations of injection molding and Analysis of Variance(ANOVA) with orthogonal array was used as a design tool to optimize the cooling system parameters aimed at minimizing the part warpage. The design optimizer was applied to find the optimum levels of cooling system parameters for a dustpan. This optimization resulted in more uniform temperature distribution over the part and significant reduction of a part warpage, showing the capability of present method as an effective design tool. The whole optimization process was performed systematically in a proper number of cooling simulations. The design optimizer can be utilized effectively in the industry practice for designing mold cooling system with less cost and time.