• Nuclear Engineering and Technology
• /
• v.35 no.1
• /
• pp.25-34
• /
• 2003

The research on the development of the fault monitoring system for the thermal reduction reactor has been performed preliminarily in order to support the successful operation of the thermal reduction reactor. The final task of the development of the fault monitoring system is to assure the integrity of the thermal$_3$ reduction reactor by the acoustic emission (AE) method. The objectives of this paper are to identify and characterize the fault-induced signals for the discrimination of the various AE signals acquired during the reactor operation. The AE data acquisition and analysis system was constructed and applied to the fault monitoring of the small- scale reduction reactor, Through the series of experiments, the various signals such as background noise, operating signals, and fault-induced signals were measured and their characteristics were identified, which will be used in the signal discrimination for further application to full-scale thermal reduction reactor.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.6
• /
• pp.815-824
• /
• 2011

In this study, a non-thermal plasma system was employed to simultaneously remove odorous compounds and organic sludge. The system consisted of two reactors; the first one was the non-thermal plasma reactor where ozone was produced by the plasma reaction and the ozone oxidized hydrogen sulfide, the model odorous compound, and then the ozone-laden gas stream was introduced to the second reactor where wasted sludge was disintegrated and solubilized by ozone oxidation. In this study, the gas retention time (GRT) and the hydraulic retention time (HRT) were changed in the two-reactor system, and the effects of GRT and HRT on reduction efficiencies of odor and sludge were determined. As the GRT increased, the ozone concentration increased resulting in an increasing efficiency of hydrogen sulfide removal. However, the overall ozone loading rate to the second sludge reactor was the same at any GRT, which resulted in an insignificant change in sludge reduction rate. When HRTs in the sludge reactor were 1, 2, 4 hours, the sludge reduction rates were approximately 30% during the four-hour operation, while the rate increased to 70% at the HRT of 6 hours. Nevertheless, at HRTs greater than 4 hours, the solubilization efficiency was not proportionally increased with increasing specific input energy, indicating that an appropriate sludge retention time needs to be applied to achieve effective solubilization efficiencies at a minimal power consumption for the non-thermal plasma reaction.

• Nuclear Engineering and Technology
• /
• v.52 no.3
• /
• pp.469-476
• /
• 2020

Research reactors in-core experimental facilities are designed to provide the highest steady state flux for user's irradiation requirements. However, fuel conversion from highly enriched uranium (HEU) to low enriched uranium (LEU) driven by the ongoing effort to diminish proliferation risk, will impact reactor physics parameters. Preserving the reactor capability to produce the needed flux to perform its intended research functions, determines the conversion feasibility. This study investigates the neutron flux in the central experimental facility of two material test reactors (MTR), the IAEA generic10 MW benchmark reactor and the 22 MW s Egyptian Test and Research Reactor (ETRR-2). A 3D full core model with three uranium enrichment of 93%, 45%, and 20% was constructed utilizing the OpenMC particle transport Monte Carlo code. Neutronics calculations were performed for fresh fuel, the beginning of life cycle (BOL) and end of life cycle (EOL) for each of the three enrichments for both the IAEA 10 MW generic reactor and core 1/98 of the ETRR-2 reactor. Criticality calculations of the effective multiplication factor (K_eff) were executed for each of the twelve cases; results show a reasonable agreement with published benchmark values for both reactors. The thermal, epithermal and fast neutron fluxes were tallied across the core, utilizing the mesh tally capability of the code and are presented here. The axial flux in the central experimental facility was tallied at 1 cm intervals, for each of the cases; results for IAEA 10 MW show a maximum reduction of 14.32% in the thermal flux of LEU to that of the HEU, at EOL. The reduction of the thermal flux for fresh fuel was between 5.81% and 9.62%, with an average drop of 8.1%. At the BOL the thermal flux showed a larger reduction range of 6.92%-13.58% with an average drop of 10.73%. Furthermore, the fission reaction rate was calculated, results showed an increase in the peak fission rate of the LEU case compared to the HEU case. Results for the ETRR-2 reactor show an average increase of 62.31% in the thermal flux of LEU to that of the HEU due to the effect of spectrum hardening. The fission rate density increased with enrichment, resulting in 34% maximum increase in the HEU case compared to the LEU case at the assemblies surrounding the flux trap.

• 한국연소학회:학술대회논문집
• /
• 2001.11a
• /
• pp.169-178
• /
• 2001

Among the recent research ideas to reduce hydrocarbon emissions emitted from SI engines till light-off of catalyst since cold start are those exploiting non-thermal plasma technique and photo-catalyst that draws recent attention by virtue of its successful application to practical use to clean up the atmosphere using the feature of its relative independence on temperature. Based on the previous research results obtained with model exhaust gases using an experimental emissions reduction system that utilizes the non-thermal plasma and photo-catalyst technique, further investigation was conducted on a production N/A 1.5 liter DOHC engine during cold start to warm-up. For the effects of non-thermal plasma-photocatalyst combined reactor, 10% concentration reduction was achieved with the fuel component paraffins, and the large increase in non-fuel paraffinic components and acetylene concentrations were similar to those of base condition. However the absolute value was locally a bit higher than those of base condition since the products was made from the dissociation and decomposition of highly branched paraffins by plasma-photocatalyst reactor. Olefinic components were highly decomposed by about 75%, due to these excellent decompositions of olefins which have relatively high MIR values, and the SR value was 1.87 that is 30% reduction from that of base condition, then, the photochemical reactivity was lowered.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.776-779
• /
• 2003

To reduce the storage space of spent fuel used at the atomic power plants in the over the world, the uranium elements contained in the spent fuel is being extracted and effectively stored. For this, the spent fuel are oxidized and deoxidized. In this study, it is produced the heat-resisting methods about the spent fuel management technology research and test facility for the spent fuel waste for spent fuel minimized. The first considered processes in the facility are the electrolytic metal reduction reactor process. Since the electrolytic metal reduction reactor is operated at the high temperature range, we have to consider the heat-resisting methods for the devices. For the heat-resisting methods, we have searched and analyzed technical reference for the heat-resisting methods. We have calculated thermal stress and strain of each devices by the commercial analysis software, ANSYS. D.S. It is experimented for inspecting confidence rate of analysis results. By using the results, we have analyzed the problems of parts and determined the heat-resisting material, commercial parts, and the size of parts and O-ring. Based on these results, it is produced the heat-resisting methods of magnesia filter, cathode, and reactor for the electrolytic metal reduction reactor.

• Journal of the Korean Solar Energy Society
• /
• v.37 no.5
• /
• pp.27-37
• /
• 2017

In this study, an artificial solar simulator composed of a 2.5 kW Xe-Arc lamp and mirror reflector was used to carry out the solar thermal two step thermochemical water decomposition cycle which can produce high efficiency continuous hydrogen production. Through various operating conditions, the change of hydrogen production due to the possibility of a dual-zone reactor and heat recovery were experimentally analyzed. Based on the reaction temperature of Thermal-Reduction step and Water-Decomposition step at $1,400^{\circ}C$ and $1,000^{\circ}C$ respectively, the hydrogen production decreased by 23.2% under the power off condition, and as a result of experiments using heat recovery technology, the hydrogen production increased by 33.8%. Therefore, when a thermochemical two-step water decomposition cycle is conducted using a dual-zone reactor with heat recovery, it is expected that the cycle can be operated twice over a certain period of time and the hydrogen production amount is increased by at least 53.5% compared to a single reactor.

• Journal of ILASS-Korea
• /
• v.25 no.3
• /
• pp.132-138
• /
• 2020

N₂O is hazardous atmosphere pollution matter which can damage the ozone layer and cause green house effect. There are many other nitrogen oxide emission control but N₂O has no its particular method. Preventing further environmental pollution and global warming, it is essential to control N₂O emission from industrial machines. In this study, the thermal decomposition experiment of N₂O gas mixture is conducted by using cylindrical reactor to figure out N₂O reduction and NO formation. And CHEMKIN calculation is conducted to figure out reaction rate and mechanism. Residence time of the N₂O gas in the reactor is set as experimental variable to imitate real SNCR system. As a result, most of the nitrogen components are converted into N2. Reaction rate of the N₂O gas decreases with N₂O emitted concentration. At 800℃ and 900℃, N₂O reduction variance and NO concentration are increased with residence time and temperature. However, at 1000℃, N₂O reduction variance and NO concentration are deceased in 40s due to forward reaction rate diminished and reverse reaction rate appeared.

• 한국연소학회:학술대회논문집
• /
• 2012.11a
• /
• pp.75-78
• /
• 2012

Rotary kiln furnace is one of the most widely used reactors in industrial field. In this paper, 0-dimensional heat and mass balance for direct coal flame rotary kiln was performed preferentially, then a simplified 1-dimensional model was developed based on 0-dimensional analysis data to proceed additional thermal analysis. Compared the results with the currently operating rotary kiln data to validate 1-dimensional model. Through this procedure, it can help to derive fundamental idea for design and operation of rotary kiln.

• Journal of Korean Society on Water Environment
• /
• v.28 no.6
• /
• pp.781-785
• /
• 2012

This study was carried out to treat the thermal elutriated acids of piggery wastewater using UASB process. The UASB reactor was operated at an organic loading rate (OLR) of $7.4\;kgCOD/m^3-day$ (6.5 ~ 9.0). During the start-up period, the low COD removal efficiency (20%) was caused by shock loading and instability in the reactor. It was mainly due to the high concentration amounts of ammonia nitrogen, which caused inhibitory and toxic effects to toward the anaerobic bacteria. In steady state, the UASB reactor showed a SCOD removal efficiency of 71% and a VS removal efficiency of 39%. The gas production and methane content were 1.3 L/day $(0.21\;m^3\;CH^4/kg$ COD removed) and 77%, respectively.

• Nuclear Engineering and Technology
• /
• v.31 no.4
• /
• pp.408-422
• /
• 1999

To reduce the fast neutron fluence which deteriorates the RPV integrity, additional shields were assumed to be installed at the outer core structures of the Kori Unit 1 reactor, and its reduction effects were examined. Full scope Monte Carlo simulation with MCNP4A code was made to estimate the fast neutron fluence at the RPV. An optimized design option was found from various choices in geometry and material for shield structure. It was expected that magnitude of fast neutron fluence would be reduced by 39% at the circumferential weld of the RPV, resulting in extension of plant lifetime by 4.6 EFPYs based on the criterion of PTS requirement It was investigated that the nuclear characteristics and thermal hydraulic factors at the internal core were only negligibly influenced by the installation of additional shield structure.