Proposed Revision to Nuclear Piping Thermal Expansion Stress Limit

Volume 3: Design and Analysis ◽

10.1115/pvp2007-26102 ◽

2007 ◽

Author(s):

Gerry C. Slagis

Keyword(s):

Thermal Expansion ◽

Creep Strain ◽

Failure Mode ◽

Expected Number ◽

Fatigue Cycling ◽

Temperature Cycles ◽

Stress Limit ◽

Full Temperature ◽

Approximate Limit

Piping thermal expansion stress limits for ASME Section III Class 2/3 piping are directly based on the original thermal expansion stress rules given in B31.1-1955. Cyclic thermal expansion stresses are limited by Equation 10 to SA where SA is a function of the expected number of full temperature cycles. The Eq. 10 limit may be exceeded, if the pressure-plus-weight stresses are below their limit. This requirement is expressed as Eq. 11. The basis for Eqs. 10 and 11 is not well understood in the industry, and has caused confusion. One typical comment is — Why have an Eq. 10 limit if it can be exceeded? The history and development of the thermal expansion stress limits are presented. The thermal expansion stress limits from B31.1 are based on relaxation considerations and prevention of yield or creep strain even though the failure mode of concern is fatigue cycling. Hence, the thermal expansion stress limit is an implied and approximate limit on fatigue. Recommendations for changes to the Section III Class 2/3 rules are provided. A direct fatigue based stress limit is proposed.

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Effect of Temperature Cycles on the Critical Current Density of YBa2Cu3O7-δ

MRS Proceedings ◽

10.1557/proc-99-365 ◽

1987 ◽

Vol 99 ◽

Cited By ~ 1

Author(s):

T. H. Tiefel ◽

S. Jin ◽

R. C. Sherwood ◽

R. A. Fastnacht ◽

S. Nakahara ◽

...

Keyword(s):

Thermal Expansion ◽

Strong Field ◽

Effect Of Temperature ◽

Weak Links ◽

Zero Field ◽

Transmission Electron Microscopy Analysis ◽

Temperature Cycles ◽

Heating And Cooling ◽

Transmission Electron ◽

Electron Microscopy Analysis

ABSTRACTThe transport Jc of the polycrystalline YBa2Cu3O7-δ superconductor seems to be dominated by weak links between high Jc regions as evidenced by low Jc values and their strong field dependence. The possible effects of thermal expansion-contraction and the tetragonal-orthorhombic transformation on the weak links and the Jc values were investigated by repeated thermal cycling of sintered pellets between -196°C and various high temperatures (600–850°C) using a furnace heating and cooling in an oxygen atmosphere. While more than a five-fold decrease in Jc from -400 to -70 A/cm2 (at 77K in zero field) is observed after 5 temperature cycles between -196'C and 850°C, only a slight decrease (to -370 Atm2) is noticed after 5 cycles between -196*C to 600°C, the temperature span of which is not all that much smaller than the former cycles. Transmission electron microscopy analysis clearly indicates that the drastic deterioration in Jc by repeated phase transformation is caused by increased amount of microcracks on (001) basal planes near the grain boundaries. The results will be discussed in terms of the large thermal expansion anisotropy of this layer-structured compound.

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Thermal expansion and crystal structure of cementite, Fe3C, between 4 and 600 K determined by time-of-flight neutron powder diffraction

Journal of Applied Crystallography ◽

10.1107/s0021889803024695 ◽

2004 ◽

Vol 37 (1) ◽

pp. 82-90 ◽

Cited By ~ 140

Author(s):

I. G. Wood ◽

Lidunka Vočadlo ◽

K. S. Knight ◽

David P. Dobson ◽

W. G. Marshall ◽

...

Keyword(s):

Crystal Structure ◽

Thermal Expansion ◽

Powder Diffraction ◽

Coefficient Of Thermal Expansion ◽

Mean Field Theory ◽

Mean Field ◽

Neutron Powder Diffraction ◽

Ferromagnetic Phase ◽

Ferromagnetic Phase Transition ◽

Full Temperature

The cementite phase of Fe3C has been studied by high-resolution neutron powder diffraction at 4.2 K and at 20 K intervals between 20 and 600 K. The crystal structure remains orthorhombic (Pnma) throughout, with the fractional coordinates of all atoms varying only slightly (the magnetic structure of the ferromagnetic phase could not be determined). The ferromagnetic phase transition, withTc≃ 480 K, greatly affects the thermal expansion coefficient of the material. The average volumetric coefficient of thermal expansion aboveTcwas found to be 4.1 (1) × 10−5 K−1; belowTcit is considerably lower (< 1.8 × 10−5 K−1) and varies greatly with temperature. The behaviour of the volume over the full temperature range of the experiment may be modelled by a third-order Grüneisen approximation to the zero-pressure equation of state, combined with a magnetostrictive correction based on mean-field theory.

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Effect of irradiation creep strain on the coefficient of thermal expansion of AGL IM1-24 and UCAR GCMB nuclear graphite moderator bricks

Nuclear Future ◽

10.1680/nuen.40.1.19.39960 ◽

2001 ◽

Vol 40 (1) ◽

pp. 19-21

Author(s):

D. A. J. Carter

Keyword(s):

Thermal Expansion ◽

Creep Strain ◽

Coefficient Of Thermal Expansion ◽

Irradiation Creep ◽

Nuclear Graphite ◽

Graphite Moderator

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Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089123 ◽

1991 ◽

Vol 49 ◽

pp. 962-963

Author(s):

J. Cooper ◽

O. Popoola ◽

W. M. Kriven

Keyword(s):

Thermal Expansion ◽

Phase Transformation ◽

Glass Matrix ◽

Nickel Sulfide ◽

Plate Glass ◽

Thermal Expansion Mismatch ◽

Volume Increase ◽

Β Phase ◽

Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

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Analytical electron microscopy of grain boundaries in Al-Cu metallizations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100133059 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1684-1685

Author(s):

J. R. Michael ◽

A. D. Romig ◽

D. R. Frear

Keyword(s):

Electron Microscopy ◽

Integrated Circuits ◽

Failure Mode ◽

Current Density ◽

Thermal History ◽

Analytical Electron Microscopy ◽

Cu Metallization ◽

Analytical Electron ◽

Interconnect Lines

Al with additions of Cu is commonly used as the conductor metallizations for integrated circuits, the Cu being added since it improves resistance to electromigration failure. As linewidths decrease to submicrometer dimensions, the current density carried by the interconnect increases dramatically and the probability of electromigration failure increases. To increase the robustness of the interconnect lines to this failure mode, an understanding of the mechanism by which Cu improves resistance to electromigration is needed. A number of theories have been proposed to account for role of Cu on electromigration behavior and many of the theories are dependent of the elemental Cu distribution in the interconnect line. However, there is an incomplete understanding of the distribution of Cu within the Al interconnect as a function of thermal history. In order to understand the role of Cu in reducing electromigration failures better, it is important to characterize the Cu distribution within the microstructure of the Al-Cu metallization.

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