Mass flow rate sensitivity and uncertainty analysis in natural circulation boiling water reactor core from Monte Carlo simulations

Research on influencing factors of CHF in narrow rectangular channel under natural circulation is of great significance to the safety of reactors. Taking the narrow rectangular experimental device as the research object, influencing factors of CHF in narrow rectangular channel were experimentally studied under natural circulation. With factorial analysis, effects of different factors and their interactions on CHF were analyzed. It is found that the contribution rate of mass flow rate is the largest, followed by the effect of outlet dryness, followed by the effect of system pressure. Their interactions between different factors have little effects on CHF in narrow rectangular channel under natural circulation.

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Detailed Evaluation of the Natural Circulation Mass Flow Rate of Water Propelled by Using an Air Injection

Journal of Nuclear Science and Technology ◽

10.1080/18811248.2008.9711432 ◽

2008 ◽

Vol 45 (3) ◽

pp. 238-243 ◽

Cited By ~ 2

Author(s):

Rae-Joon PARK ◽

Kwang-Soon HA ◽

Jae-Cheol KIM ◽

Seong-Wan HONG ◽

Sang-Baik KIM

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Natural Circulation ◽

Air Injection ◽

Detailed Evaluation

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Direct Simulation Monte Carlo Solution of Subsonic Flow Through Micro/Nanoscale Channels

Journal of Heat Transfer ◽

10.1115/1.3139105 ◽

2009 ◽

Vol 131 (9) ◽

Cited By ~ 40

Author(s):

Ehsan Roohi ◽

Masoud Darbandi ◽

Vahid Mirjalili

Keyword(s):

Monte Carlo ◽

Boundary Conditions ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Analytical Solutions ◽

Direct Simulation Monte Carlo ◽

Direct Simulation ◽

Channel Outlet ◽

Simulation Monte Carlo

We use a direct simulation Monte Carlo (DSMC) method to simulate gas heating/cooling and choked subsonic flows in micro/nanoscale channels subject to either constant wall temperature or constant/variable heat flux boundary conditions. We show the effects of applying various boundary conditions on the mass flow rate and the flow parameters. We also show that it is necessary to add a buffer zone at the end of the channel if we wish to simulate more realistic conditions at the channel outlet. We also discuss why applying equilibrium-based Maxwellian distribution on molecules coming from the channel outlet, where the flow is nonequilibrium, will not disturb the DSMC solution. The current velocity, pressure, and mass flow rate results are compared with different analytical solutions of the Navier–Stokes equations. Although there are good agreements between the DSMC results and the analytical solutions in low compressible flow, the analytical solutions yield incorrect velocity and mass flow rate values in short micro/nanochannel flows with high compressibility and/or choked flow conditions.

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Research on Natural Circulation Flow Characteristics of Floating Nuclear Power Plant in Heaving Motion

Volume 5: Advanced and Next Generation Reactors, Fusion Technology; Codes, Standards, Conformity Assessment, Licensing, and Regulatory Issues ◽

10.1115/icone25-66240 ◽

2017 ◽

Author(s):

Li Ren ◽

Peng Minjun ◽

Xia Genglei ◽

Zhao Yanan

Keyword(s):

Power Plant ◽

Nuclear Power Plant ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Nuclear Power ◽

Natural Circulation ◽

Flow Characteristics ◽

Circulation Flow ◽

Drift Flux Model

The FNPP (Floating Nuclear Power Plant) expanded the application field of Integrated Pressurized Water Reactor (IPWR) in the movable marine platform, it is necessary to study the natural circulation flow characteristics in heaving motion on the ocean. From the characteristics of FNPP, by means of THEATRe code which was based on the two-phase drift flux model and was modified by adding module calculating the effect of heaving motion, the simulation model in heaving motion was built. Using the models developed, the natural circulation operating characteristics of natural circulation in heaving motion and the transitions between forced circulation and natural circulation are analyzed. In the case of amplitude limited, the periods of mass flow rate are equal to periods of heaving motion. The oscillation amplitude of mass flow rate increases with the heaving amplitude increase. In the case of period limited, the natural circulation flow rate oscillating amplitude increases with the heaving period increases. The result obtained are not only evaluating FNPP design behavior properly but also pointing out the direction to further optimum design to ensure FNPP operating safety in heaving motion.

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ANALISIS DESAIN PROSES SISTEM PENDINGIN PADA REAKTOR RISET INOVATIF 50 MW

JURNAL TEKNOLOGI REAKTOR NUKLIR TRI DASA MEGA ◽

10.17146/tdm.2015.17.1.2235 ◽

2015 ◽

Vol 17 (1) ◽

pp. 19 ◽

Cited By ~ 1

Author(s):

Sukmanto Dibyo ◽

Endiah Puji Hastuti ◽

Ign. Djoko Irianto

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Cooling System ◽

Reactor Core ◽

Material Testing ◽

Thermal Design ◽

Coolant Pump ◽

Energy Balances ◽

Coolant System

Reaktor Riset Inovatif (RRI) merupakan jenis MTR (Material Testing Reactor) yang dipersiapkan ke depan sebagai desain reaktor baru. Daya RRI telah ditetapkan dari perhitungan neutronik dan termohidrolika teras yaitu 50 MW termal. Reaktor bertekanan 8 kgf/cm2 dan laju aliran massa pendingin primer 900 kg/s. Tantangan yang penting dalam menindak lanjuti desain reaktor ini adalah analisis desain pada sistem pendingin. Makalah ini bertujuan untuk menganalisis desain proses sistem pendingin utama reaktor RRI daya 50 MW (RRI-50) dengan menggunakan program Chemcad 6.1.4. Dalam analisis ini dilakukan perhitungan neraca massa dan energi (mass/energy balances) pada sistem pendingin primer dan sekunder sebagai pendingin utama. Masing-masing sistem pendingin tersebut terdiri dari 2 jalur beroperasi secara paralel dan 1 jalur redundansi. Disamping itu untuk desain termal unit komponen telah dianalisis dengan program RELAP5, frenchcreek dan Metoda Analitik. Hasil analisis yang diperoleh adalah desain diagram sistem pendingin yang mencakup data parameter entalpi, temperatur, tekanan dan laju aliran massa pendingin untuk masing-masing jalur. Adapun hasil desain unit komponen utama pada RRI-50 adalah tangki tunda dengan volume 51,5 m3, 2 unit pompa sentrifugal dan 1 unit pompa cadangan pada pendingin primer daya 141 kW/pompa dan pendingin sekunder daya 206 kW/pompa, 2 unit penukar panas tipe shell-tube dengan koefisien termal overall 1377 W/m2.oC dan 4 unit menara pendingin yang mampu melepaskan panas ke udara dengan desain temperatur approach 5,0 oC dan temperatur range 9,0 oC. Desain sistem pendingin reaktor RRI-50 ini telah menetapkan parameter operasi sistem pendingin yaitu temperatur, tekanan dan laju aliran massa pendingin dengan mempertimbangkan tuntutan aspek keselamatan teras reaktor sehingga desain temperatur maksimum pendingin masuk ke teras 44,5 oC. Kata kunci : RRI 50 MW, desain sistem pendingin, program Chemcad 6.1.4 Innovative Research Reactor RRI is a type of MTR (Material Testing Reactor), which is being prepared in the future as a design of new reactor. The power of RRI has been determined based on the core thermalhydraulic and neutronic calculation, which is 50 MWt. The reactor pressure is 8 kgf/cm 2 and coolant mass flow rate is 900 kg/s. The important challenge in the follow up of this reactor design is the design analysis of cooling system. The purpose of this study is to analyze the design of RRI reactor main coolant system at the power of 50 MWt (RRI-50) using ChemCAD 6.1.4. In this analysis the mass and energy balances at the primary and secondary cooling system are calculated as main coolant. Each of the cooling system consists of two lines operating in parallel and redundancy lines. Besides that, the thermal design of the component units have been analyzed using RELAP5, FrenchCreek and Analytical Methods. The analyses result obtained is a design of cooling system diagram which includes parameter of enthalpy, temperature, pressure and coolant mass flow rate of each line. Meanwhile, design result of main component unit are delay tank of 51.5 m3 volume, 2 unit centrifugal pumps and 1 unit stand-by pump for the primary coolant pump each of 141 kW power and secondary coolant pump each of 206 kW power, 2 unit of shell-tube heat exchanger with overall thermal coefficient of 1377 W/m2.oC and 4 unit cooling tower that capable to release the heat to the air at approach temperature of 5,0 oC and range temperature of 9,0 oC. design of reactor coolant system RRI-50 has decided the operating parameters of cooling system are temperature, pressure and mass flow rate by considering into the demands of the safety aspects of the reactor core therefore design of maximum coolant temperature to the reactor core is 44,5 oC. Keywords : RRI 50MW, design of cooling system, program Chemcad 6.1.4.

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Assessment of Modified RELAP5 MOD3.2 Against LBE Natural Circulation Test Loops

Frontiers in Energy Research ◽

10.3389/fenrg.2021.674353 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yufeng Lv ◽

Xingmin Liu ◽

Weihan Li ◽

Chunqiu Guo ◽

Zhiwei Zhou

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Natural Circulation ◽

Hydraulic Analysis ◽

Original Performance ◽

Nuclear Systems ◽

Simulation Results ◽

Thermal Hydraulic Analysis ◽

Thermo Physical Properties

Motivated by the significant natural circulation capability of lead–bismuth eutectic (LBE)–cooled systems, the RELAP5 MOD3.2 code was modified for the analysis of LBE-cooled reactors and non-nuclear systems. The thermo-physical properties of LBE have been incorporated into the code without affecting the code’s original performance; new heat transfer correlations for liquid metal have been implemented. For the purpose of validating the modified code, experimental results of two different LBE natural circulation test loops were compared with the code simulation results. The first one was a natural circulation setup process test at a power of 22.5 kW performed at the Natural Circulation Experimental (NACIE) facility. The simulated inlet and outlet LBE temperatures across the heat source and mass flow rate of LBE agreed well with the test data. The second one was natural circulation conditions under five different power levels conducted at the Natural Circulation Capability Loop (NCCL) facility. The LBE temperature difference and mass flow rate under different power levels predicted by the code were consistent with the experimental data. Generally speaking, the modified code gives acceptable results, and the code could be applied for further LBE systems thermal-hydraulic analysis.

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Two-phase natural circulation loop behaviour at atmospheric and subatmospheric conditions

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/0954408918787401 ◽

2018 ◽

Vol 233 (4) ◽

pp. 687-700

Author(s):

S Venkata Sai Sudheer ◽

K Kiran Kumar ◽

Karthik Balasubramanian

Keyword(s):

Heat Flux ◽

Physical Properties ◽

Spatial Variation ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Natural Circulation ◽

Two Phase ◽

Natural Circulation Loop ◽

Thermo Physical Properties

This paper aims to present the steady-state behaviour of two-phase natural circulation loop at atmospheric and sub-atmospheric conditions. One-dimensional numerical approach is adopted to evaluate various system parameters, with special emphasis on spatial variation of thermo-physical properties and flashing. Homogeneous equilibrium model is applied for two-phase flows. An in-house code is developed in MATLAB to solve numerical model iteratively. It is observed that consideration of spatial variation of thermo-physical properties can precisely predict the loop behaviour. The evaluated results are validated with the open literature and reasonably good agreement is observed. The heater inlet temperature, inlet pressure and heat flux are found to have significant influence on spatial variation of pressure, temperature and enthalpy. As system pressure decreases from atmospheric to sub-atmospheric (1–0.8 atm), it is observed that the sub-atmospheric loop gives a higher mass flow rate compared to atmospheric loop at lower heat fluxes. However, as the heat flux increases in the sub-atmospheric loop, the mass flow rate is reduced due to increased drag force in the loop.

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Steady-State Energetic and Exergetic Performances of Single-Phase Natural Circulation Loop With Hybrid Nanofluids

Journal of Heat Transfer ◽

10.1115/1.4043819 ◽

2019 ◽

Vol 141 (8) ◽

Cited By ~ 13

Author(s):

Mayaram Sahu ◽

Jahar Sarkar

Keyword(s):

Steady State ◽

Mass Flow Rate ◽

Entropy Generation ◽

Mass Flow ◽

Flow Rate ◽

Natural Circulation ◽

Circulation Loop ◽

Hybrid Nanofluid ◽

Natural Circulation Loop ◽

Hybrid Nanofluids

Energy and exergy performances of natural circulation loop (NCL) with various water-based hybrid nanofluids (Al2O3 + TiO2, Al2O3 + CNT, Al2O3 + Ag, Al2O3 + Cu, Al2O3 + CuO, Al2O3 + graphene) with 1% volumetric concentration are compared in this study. New thermophysical property models have been proposed for hybrid nanofluids with different particle shapes and mixture ratio. Effects of power input, loop diameter, loop height, loop inclination and heater/cooler inclination on steady-state mass flow rate, effectiveness, and entropy generation are discussed as well. Results show that both the steady-state mass flow rate and energy–exergy performance are enhanced by using the hybrid nanofluids, except Al2O3 + graphene, which shows the performance decrement within the studied power range. Al2O3 + Ag hybrid nanofluid shows highest enhancement in mass flow rate of 4.8% compared to water. The shape of nanoparticle has shown a significant effect on steady-state performance; hybrid nanofluid having cylindrical and platelet shape nanoparticles yields lower mass flow rate than that of spherical shape. Mass flow rate increases with the increasing loop diameter and height, whereas decreases with the increasing loop and heater/cooler inclinations. Both effectiveness and entropy generation increase with the decreasing loop diameter and height, whereas increasing the loop and heater/cooler inclinations. This study reveals that the particle shape has a significant effect on the performance of hybrid nanofluids in NCL, and the use of hybrid nanofluid is more effective for higher power.

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