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경수로핵연료기술개발부 LWR Fuel Development Division
2013.12.06
곽영균, 인왕기
한국원자력연구원
CFD를 이용한 건식저장 사용후핵연료의 국소온도 예측
CFD Prediction of Local Temperature on the Spent Fuel in a Dry
Storage
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경수로핵연료기술개발부 LWR Fuel Development Division
2
The spent fuel pool is expected to be full in few years.
- It is a serious problem one should not ignore.
- The dry storage type is considered as the interim storage
system
It would be of great interest to investigate the maximum fuel
temperature in a dry
storage system.
- The spent fuel is heated by decay heat.
- Cooling by a natural convection system, radiation, and
conduction
Integrity assessment of a dry storage system
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경수로핵연료기술개발부 LWR Fuel Development Division
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Investigation on thermal hydraulic characteristics of spent fuel
in a dry storage
system using the CFD method.
Prediction and assessment of 3D heat flow distribution and fuel
rod temperature
for a dry storage system and the fuel assembly
Objectives
Import B.C.
Dry storage system of spent fuel(32 FA) Full fuel assembly
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경수로핵연료기술개발부 LWR Fuel Development Division
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CFD code: ANSYS CFX(v14.0), Star-CCM+(v7.0~v8.04)
Grids generation:[(Tetrahedral, Polyhedral, Trimmer)+Prism
Layer]
Natural convection: Boussinesq model
Radiation model:
CFX(P1, Rosseland, Discrete Transfer Model, Monte-Carlo
model)
Star-CCM+(Surface-to-Surface model, Discrete Ordinate
Method)
CFD code assessment
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경수로핵연료기술개발부 LWR Fuel Development Division
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4,200
100
100
Domain : 208.82 x 208.82(32ea) Total diameter:1,700 mm
CFX ver. 14.0
Grids generation
- Quadrilateral mesh + Sweep method
- Nodes: 3,774,108
B.C.
- Working fluid: Helium(300K)
- Spent fuel assembly : Porous media
- Loss coefficient: 5.875 /m
- Source: 9.06kW/m3(1.6kW/FA)
- Outside walls: 320K
- Natural convection: Boussinesq model
- Radiation model: P1 Dry storage system of spent fuel(32
FA)
Numerical model and boundary conditions
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경수로핵연료기술개발부 LWR Fuel Development Division
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Numerical model and boundary conditions
Mid-grid with mixing-vane(9)
Bottom grid
Top grid
Spring & Dimple
16x16 FA (236-fuel rods & 5-guide tubes)
Full fuel assembly
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경수로핵연료기술개발부 LWR Fuel Development Division
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Numerical model and boundary conditions
STAR-CCM+ ver. 8.02
Grids generation
-Trimmer mesh
-Nodes: 193,017,547
B.C.
-Working fluid: Helium
-Inlet and outlet: Values given from the results
of the dry storage system
-Fuel: Heat flux, 56W/m2(1.6kW/FA)
-Natural convection: Full buoyancy model
-Radiation model: S2S model
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경수로핵연료기술개발부 LWR Fuel Development Division
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The inlet temperature of the outer bundle was higher because of
a temperature increase from
natural convection.
In the contrast with the inlet, the inner bundle temperature is
higher at the outlet.
There is a stagnation region at the middle of the outer
bundle
Temperature and velocity of each bundle
Results of the dry storage system
Inlet Middle Outlet
T[K] V[m/s] T[K] V[m/s] T[K] V[m/s]
A 402 0.35 482 0.54 514 0.24
B 414 0.37 481 0.55 511 0.27
C 419 0.30 479 0.46 508 0.28
D 424 0.22 477 0.24 505 0.28
E 424 0.19 551 0.19 502 0.26
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경수로핵연료기술개발부 LWR Fuel Development Division
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Results of the dry storage system
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경수로핵연료기술개발부 LWR Fuel Development Division
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Results of the dry storage system
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경수로핵연료기술개발부 LWR Fuel Development Division
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The temperature was spread out by a spacer grid.
The axial velocities at the corners of the fuel assembly were
the fastest. These result in a
decrease in temperature
In contrast, the temperature of the center fuel assembly was
higher.
Maximum temperature: 706K(433℃)
Velocity vector and Temperature distribution
Results of the full assembly
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경수로핵연료기술개발부 LWR Fuel Development Division
12
The inlet temperature of the outer bundle was higher because of
a temperature increase from
natural convection.
There is a stagnation region at the middle of the outer
bundle
The temperature was spread out by a spacer grid.
The axial velocities at the corners of the fuel assembly were
the fastest. These result in a
decrease in temperature
In contrast, the temperature of the center fuel assembly was
higher.
Maximum temperature: 706K(433℃)
Summary
