Post on 17-Feb-2019
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Design Study of Innovative Simplified Small Pebble Bed Reactor
Dwi Irwanto1) and Toru OBARA2)
1)Department of Nuclear Engineering, Tokyo Institute of Technology2)Research Laboratory for Nuclear Reactor, Tokyo Institute of Technology
• Introduction• Current research purposes• Calculation procedures• Thermal hydraulic calculation of the
reference design• Conclusion
Outline
Page 2
Introduction
page 3
(Potential) Problem ?• The unloading machinery is a very complex
and high cost system
Pebble Bed Reactor
Introduction
• Peu a Peu fuel loading concept proposed by E.Teuchert et al (1992)
• Pebble bed reactor –based design with fuel unloading devices is removed
• Startup → lower layers filled → first criticality
• During operation → layer per layer filled →maintain criticality
• The end of the core → unloaded fuel
Peu a Peu Fuel Loading Scheme
Neutronic parameters for a reference design have been calculated in the previous study *
page 4* Design Study of Innovative Simplified Small Pebble Bed Reactor (1) Design concept and sample design analysis
Calculation Procedures
• From the calculation results of the neutronic analysis (MVP/MVP-Burn), power density and power distribution inside the reactor core were obtained.
• These parameters, then uses in the calculation which conducted by porous media flow and heat transfer modules in steady state condition.
• The analysis was performed by COMSOL Multiphysics code.
page 6
Reference Design
Design Specification
Reactor Power 20 MWth
Fuel TRISO
Core radius 125 cm
Core Height 500 cm
Reflector width 70 cm
Startup fuel layers 85 cm
Initial 235Uenrichment
12 %
Supply fuel 235Uenrichment
12 %
Packing Fraction 7.0 %Schematic view of reactor core
design
page 7
Uo = 1.06 m/s ;
P = 6 x 106 Pa
Axi
al s
ymet
ry
Tin = 550oC
Helium
Tout = ?
Pin = ?
Meshing
Q from MVP
ComsolHeat Transfer
module -> General Heat Transfer
Thermal Conductivity (k)
keffective (T) W/m K
Density (ρ) 3.7012 * kg/m3
Heat CapacityCp (comsollibrary)
J/kg K
Production/ absorption coef f (qs)
0W/m3
K
Heat source (Q) (MVP) W/m3
Velocity u = 0v = -1.06
m/s
Boundary condition
T 550 oC
ComsolChemical engineering module -> momentum transport -> porous media flow
Material Helium
Density (ρ) 3.7012 * kg/m3
Dynamic viscosity (η)
eta(T) (comsollibrary) Pa.s
Permeability (κ) 1.06 x 10-7 m2
Source term (F) 0 kg/m3 s
Boundary condition
P 6.0 x 106 Pa
*The Properties of Helium: Density, Specific Heats, Viscosity, and Thermal Conductivityat Pressures from 1 to 100 bar and from Room Temperature to about 1800 KHelge Petersen, Danish Atomic Energy Commision Research Establishmen Riso, September 1970
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Calculation Results
rho * 3.7021 kg/m^3D 0.06 mviscosity 3.86E-05 Pa.sporosity 0.39Cp 5163.499 J/kg Kkf * 0.304 W/MK
Pebble Ball radius 3.00E-02 mFuel zone radius 2.50E-02 msurface pebble 1.13E-02 m^2volume pebble 1.13E-04 m^3k ** 20 W/mK
** Improving Fuel Cycle Design and Safety Characteristics of a Gas Cooled Fast Reactor, Willem Fredick Geert van Rooijen
* The Properties of Helium: Density, Specific Heats, Viscosity, and Thermal Conductivity at Pressures from 1 to 100 bar and from Room Temperature to about 1800 K ; Helge Petersen, Danish Atomic Energy Commision Research Establishmen Riso, September 1970
Calculation Results
page 11
Conclusions
• Concept of innovative small high temperature gas cooled pebble bed reactor with possibility to simplify the reactor system by removing unloading devices has been performed
• Analysis of the maximum temperature inside the pebble ball at the end of the reactor life shown that the maximum temperature is 722oC which is still far below the safety limit of 1600oC.
• Optimization in term of the power distribution and burnup characteristic are the aspects will be performed in the future using method developed in this study.
page 14