Presentation work.pptx
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Huse, Stephen
Calculate heat transfer for given initial
conditions
Calculate thermal differences and stresses
Predict the onset of thermal stress ratcheting
using FEA methods
Compare to ASME code prediction
Thermal gradients occur due to changes in
temperature of fluid flowing through piping
T - Mean Temperature
V - Linear Temperature difference, ∆T1
Peak Temperature difference
Bree Diagram Regions
◦
◦
◦
◦
E – Elastic
S – Shakedown
P - Plastic cyclic
R - Ratcheting
σp – Primary Stress, PD/2t
σt – Secondary Stress, EαΔT1/2(1-v)
◦ P – Pressure
◦ D – diameter
◦ t – thickness
◦
◦
◦
◦
E – Young’s modulus
α – Mean coefficient of thermal expansion
∆T1 – Linear temperature Difference
v – Poisson’s ratio
σy – Yield Strength
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
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
ABAQUS for solving heat transfer analysis and structural
analysis
◦ Geometry
◦ Material properties
◦ Load conditions
Stress vs strain
for iterated
pressures of 1,
2, and 3 ksi
Onset of Thermal
Ratcheting is able to
be predicted with
ABAQUS.
ABAQUS predicted
1500 psi, whereas
ASME code predicted
1300 to 1600 based
on choice of yield
strength
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.
ABAQUS (Version 6.13) [Software]. (2013).
Providence, RI: Dassault Systèmes Simulia Corp.