• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.456.1-456.1
• /
• 2014

Transmutation characteristics of transuranics (TRU) in a transmutation reactor based on LAR (Low Aspect Ratio) tokamak as a neutron source are investigated. Optimum radial build of a transmutation reactor is found by coupled analysis of the tokamak systems and the neutron transport. The dependence of the transmutation characteristics on an aspect ratio, A in the range of 1.5 to 2.5, and on a fusion power in the range of 150 MW to 500 MW are investigated. Equilibrium fuel cycle is developed for effective transmutation and it is shown that with one unit of the transmutation reactor based on the LAR tokamak producing fusion power in the range of a few hundred MW, up to 3 PWRs (1.0 GWe capacity) can be supported with the burn-up fraction bigger than 50%.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.10a
• /
• pp.299-304
• /
• 1997

A neuro-fuzzy control algorithm is applied for xenon spatial oscillations in a pressurized water reactor. The consequent and antecedent parameters of the fuzzy rules are tuned by the gradient descent mettled. The reactor model used for computer simulations is a two-point xenon oscillation model. The reactor core is axially divided into two regions and each region has one input and one output and is coupled with the other region. The interaction between the regions of the reactor core is treated by a decoupling scheme. This proposed control of mettled exhibits very fast responses to a step or a ramp change of target axial offset without any residual flux oscillations.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.311.2-311.2
• /
• 2013

Transmutation characteristics of minor actinides in a transmutation reactor based on a Low Aspect Ratio (LAR) tokamak are investigated. One-dimensional neutron transport and burn-up calculation coupled with the tokamak systems analysis were performed to find the optimal system parameters. The dependence of the transmutation characteristics such as neutron multiplication factor, produced power and transmutation rate on an aspect ratio A in the range of 1.5 to 2.0 was investigated. By adding Pu239 in the transmutation blanket as a neutron multiplication material, it was shown that the one unit of the transmutation reactor based on the LAR tokamak producing fusion power of 150 MWth can destroy the minor actinides contained in the spent fuels produced from more than 19 units of l GWe PWRs with production of the power being in the range of 0.9 - 3.4 GWth.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.414.2-414.2
• /
• 2016

The optimal configuration of a transmutation reactor based on a low aspect ratio tokamak is determined using coupled analysis of tokamak systems and neutron transport. The inboard radial build of the reactor components is obtained from plasma physics and engineering constraints, while outboard radial builds are mainly determined by constraints on a neutron multiplication, a tritium-breeding ratio, and a power density. It is shown that a breeding blanket model has an impact on the radial build of a transmutation blanket. A burn cycle has to be determined to limit a fast neutron fluence of a plasma facing material below a radiation damage limit.

• Journal of computational fluids engineering
• /
• v.21 no.3
• /
• pp.89-97
• /
• 2016

In this study, direct code coupling, in which two codes share a single flow field, was conducted using 3-dimensional high resolution thermal hydraulics code, CUPID and 1-dimensional system analysis code, MARS. This approach provide the merit to use versatile capability of MARS for nuclear power plants and 3-dimensional T/H analysis capability of CUPID. Numerical Method to directly couple CUPID and MARS was described in this paper. The straight flow and manometer flow oscillation were calculated to verify conservation of coupled CUPID/MARS code in mass, momentum, and energy. This verification calculations indicates that the CUPID/MARS is coupled appropriately in numerical aspect and the coupled code can be applied to nuclear reactor thermal hydraulics after validation against integral transient experiments.

• Nuclear Engineering and Technology
• /
• v.50 no.5
• /
• pp.639-647
• /
• 2018

In this study, the effects of selecting water/silver nanofluid as both a coolant and a reactivity controller during the first operating cycle of a light water nuclear reactor are investigated. To achieve this, coupled neutronic-thermo-hydraulic analysis is employed to simulate the reactor core. A detailed VVER1000/446 reactor core is modeled in monte carlo code (MCNP), and the model is verified using the porous media approach. Results show that the maximum required level of silver nanoparticles is 1.3 Vol.% at the beginning of the cycle; this value drops to zero at the end of cycle. Due to substitution of water/boric acid with water/Ag nanofluid, reactor operation time at maximum power extends to 357.3 days, and the energy generation increases by about 27.3%. The higher negative coolant temperature coefficient of reactivity in the presence of nanofluid in comparison with the water/boric acid indicates that the reactor is inherently safer. Considering the safety margins in the presence of the nanofluid, minimum departure from nucleate boiling ratio is calculated to be 2.16 (recommendation is 1.75).

• Nuclear Engineering and Technology
• /
• v.51 no.4
• /
• pp.949-953
• /
• 2019

The burnup equation of nuclides is one of the most equations in nuclear reactor physics, which is generally coupled with transport calculations. The burnup equation describes the variation of the nuclides with time. Because of its very stiffness and the need for large time step, this equation is solved by special methods, for example transmutation trajectory analysis (TTA) or the matrix exponential methods where the matrix exponential is approximated by CRAM. However, TTA or CRAM functions well when the flux is constant. In this work, a new method is proposed when the flux changes. It's an improved method compared to TTA or CRAM. Furtherly, this new method is based on TTA or CRAM, and it is more accurate than them. The accuracy and efficiency of this method are investigated. Several cases are used and the results show the accuracy and efficiency of this method are great.

• Nuclear Engineering and Technology
• /
• v.55 no.11
• /
• pp.4266-4273
• /
• 2023

In a severe reactor accident, a crust will form on the surface of the molten material during the core melting process. The crust will have a contact melting with the internal components of the reactor. In this paper, the contact melting process of the molten material on the austenitic stainless steel plate bundles is studied. The contact melting model of parabolic molten material on the plate bundles is proposed, and the rule and main effect factors of the contact melting are analyzed. The results show that the melting velocity is proportional to the slope of the paraboloid, the heat flux and the distance between two plates D. The influence of melt gravity and the plate width on melting velocity is negligible. The thickness of the molten liquid film is proportional to the heat flux and plate width, and it is inversely proportional to the gravity. With the increase of D, the liquid film thickness decreases at first and then increases gradually. The liquid film thickness has a minimum against D. When the width of the plate is small, the width of the plate is the main factor affecting the thickness of the liquid film. The parameters are coupled with each other. In a severe reactor accident, the wider internal components of reactor, which can increase the thickness of the melting liquid film and reduce the net input heat flux from the molten material to the components, are the effective measures to delay the melting process.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.4
• /
• pp.375-381
• /
• 2010

In this paper, the heat-transfer characteristics of steam reforming in an annular reactor are presented. Heat is supplied by the catalytic combustion of syn-gas. The thermal behaviors of exothermic and endothermic reactions in a directly coupled concentric-tube packed-bed reactor were investigated experimentally. The gas mixture supplied for catalytic combustion consisted of the off-gas emitted from MCFC anode. Methane in steam at a suitable S/C (steam-to-carbon) ratio was used in the reforming reactions. On the basis of the experimental results, a simple simulation was performed to predict the temperature profile required in the reforming side of the reactor to achieve optimum hydrogen yield. The results of this study may be utilized as reference data in future studies for further development of coupled reactors.

• KSBB Journal
• /
• v.4 no.3
• /
• pp.215-220
• /
• 1989

To develop an attrition coupled enzyme reactor with high efficiency-low energy consumption for saccharification of insoluble biomass, a 5L horizontal paddle type bioreactor was constructed and its performance was evaluated. The optimal condition for saccharification of 50g $\alpha$ -cellulose/L was found to be 200rpm with 500g of 3mm glass bead. Especially, the horizontal paddle type bloreactor was very effective for saccharification of high concentration of insoluble cellulose, in which around 72% of $\alpha$ -cellulose was saccharified for 75g $\alpha$ -cellulose/L, and even up to 70% for 100g of $\alpha$ -cellulose/L after 24hours. Under the optimal condition, the power consumption was measured to be around 1.7watth/g. Horizontal paddle type bioreactor seems to have an appropriated structural feature for industrial scale operation and to be an effective and energy saving attrition coupled enzyme reactor.