Transcript Proposal slides.pptx

Huse, Stephen
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Calculate heat transfer for given initial
conditions
Calculate thermal gradients and stresses
Predict the onset of thermal stress ratcheting
using FEA methods
Compare to ASME code prediction
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Thermal gradients occur due to changes in
temperature of fluid flowing through piping
T - Mean Temperature
V - Linear Temperature Gradient, ∆T1
Peak Temperature Gradient, ∆T2
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Bree Diagram Regions
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E – Elastic
S – Shakedown
P - Plastic cyclic
R - Ratcheting
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σp – Primary Stress, PD/2t
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σt – Secondary Stress, EαΔT1/2(1-v)
◦ P – Pressure
◦ D – diameter
◦ t – thickness
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E – Young’s modulus
α – Mean coefficient of thermal expansion
∆T1 – Linear temperature gradient
v – Poisson’s ratio
σy – Yield Strength
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Nuclear power plants have high thermal
gradients and pressures resulting in sever
primary and secondary stresses
Severe primary and secondary stresses result
in accumulating plastic strains known as
thermal ratcheting
Prevention of thermal ratcheting is performed
by limiting the allowable stresses
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Convective heat transfer of turbulent flow inside a
cylinder: Nu=0.023Re0.8Prn
◦ Nu=hd/k
 h – convective heat transfer coefficient
 d – inner diameter
 k – fluid thermal conductivity
◦ Re=vd/ν
 v – velocity
 d – inner diameter
 ν – kinematic viscosity
◦ Pr – Prandtl number
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ABAQUS for solving heat transfer analysis and structural
analysis
◦ Geometry
◦ Material properties
◦ Load conditions
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Bree, J. (1967). Elastic-plastic behaviour of thin
tubes subject to internal pressure and
intermittent high-heat fluxes with application to
fast nuclear reactor fuel elements.Journal of
Strain Analysis, (2), 226-38.
2010 ASME boiler & pressure vessel code an
international code. (2010). New York, NY:
American Society of Mechanical Engineers.
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ABAQUS (Version 6.13) [Software]. (2013).
Providence, RI: Dassault Systèmes Simulia Corp.