Chromium Activity Measurements in Nickel Based Alloys for Very High Temperature Reactors: Inconel 617, Haynes 230, and Model Alloys

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Stéphane Gossé ◽  
Thierry Alpettaz ◽  
Sylvie Chatain ◽  
Christine Guéneau
Keyword(s):  
High Temperature ◽  
Heat Exchangers ◽  
Mass Spectrometric ◽  
Operating Conditions ◽  
Pure Substance ◽  
Haynes 230 ◽  
Inconel 617 ◽  
High Temperature Reactor ◽  
High Temperature Reactors ◽  
Very High

The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHXs) of (very) high temperature reactors ((V)-HTRs). The behavior under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra- and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer. The alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow (Rouillard, F., 2007, “Mécanismes de formation et de destruction de la couche d’oxyde sur un alliage chrominoformeur en milieu HTR,” Ph.D. thesis, Ecole des Mines de Saint-Etienne, France). To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T≈1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617, and model alloys 1178, 1181, and 1201. This coupling makes it possible for the thermodynamic equilibrium to be obtained between the vapor phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (I) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared with that of the pure substance (Cr) at the same temperature. These calculations provide thermodynamic data characteristic of the chromium behavior in these alloys. These activity results call into question those previously measured by Hilpert and Ali-Khan (1978, “Mass Spectrometric Studies of Alloys Proposed for High-Temperature Reactor Systems: I. Alloy IN-643,” J. Nucl. Mater., 78, pp. 265–271; 1979, “Mass Spectrometric Studies of Alloys Proposed for High-Temperature Reactor Systems: II. Inconel Alloy 617 and Nimomic Alloy PE 13,” J. Nucl. Mater., 80, pp. 126–131), largely used in the literature.

Chromium Activity Measurements in Nickel Based Alloys for Very High Temperature Reactors: Inconel 617, Haynes 230 and Model Alloys

2008 ◽  
Author(s):  
S. Gosse´ ◽  
T. Alpettaz ◽  
S. Chatain ◽  
C. Gue´neau ◽  
F. Rouillard ◽  
...  
Keyword(s):  
High Temperature ◽  
Heat Exchangers ◽  
Selection Criterion ◽  
Operating Conditions ◽  
Pure Substance ◽  
Protective Oxide ◽  
Haynes 230 ◽  
Activity Measurements ◽  
Inconel 617 ◽  
Very High

The alloys Haynes 230 and Inconel 617 are potential candidates for the intermediate heat exchangers (IHX) of (V)-HTR reactors. The behaviour under corrosion of these alloys by the (V)-HTR coolant (impure helium) is an important selection criterion because it defines the service life of these components. At high temperature, the Haynes 230 is likely to develop a chromium oxide on the surface. This layer protects from the exchanges with the surrounding medium and thus confers certain passivity on metal. At very high temperature, the initial microstructure made up of austenitic grains and coarse intra and intergranular M6C carbide grains rich in W will evolve. The M6C carbides remain and some M23C6 richer in Cr appear. Then, carbon can reduce the protective oxide layer. Then, the alloy loses its protective coating and can corrode quickly. Experimental investigations were performed on these nickel based alloys under an impure helium flow [1]. To predict the surface reactivity of chromium under impure helium, it is necessary to determine its chemical activity in a temperature range close to the operating conditions of the heat exchangers (T ≈ 1273 K). For that, high temperature mass spectrometry measurements coupled to multiple effusion Knudsen cells are carried out on several samples: Haynes 230, Inconel 617 and model alloys 1178, 1181, 1201. This coupling makes it possible thermodynamic equilibrium to be obtained between the vapour phase and the condensed phase of the sample. The measurement of the chromium ionic intensity (I) of the molecular beam resulting from a cell containing an alloy provides the values of partial pressure according to the temperature. This value is compared to that of the pure substance (Cr) at the same temperature. These calculations provide thermodynamic data characteristic of the chromium behaviour in these alloys. These activity results call into question those previously measured by Hilpert [2], largely used in the literature.

Refueling Liquid-Salt-Cooled Very High-Temperature Reactors

2006 ◽  
Author(s):  
Charles W. Forsberg ◽  
Per F. Peterson ◽  
James E. Cahalan ◽  
Jeffrey A. Enneking ◽  
Phil MacDonald
Keyword(s):  
High Temperature ◽  
Fuel Element ◽  
Operating Conditions ◽  
Plant Design ◽  
Fast Reactors ◽  
Liquid Salt ◽  
Study Results ◽  
High Temperature Reactor ◽  
High Temperature Reactors ◽  
Very High

The liquid-salt-cooled very high-temperature reactor (LS-VHTR), also called the Advanced High-Temperature Reactor (AHTR), is a new reactor concept that combines in a novel way four established technologies: (1) coated-particle graphite-matrix nuclear fuels, (2) Brayton power cycles, (3) passive safety systems and plant designs previously developed for liquid-metal-cooled fast reactors, and (4) low-pressure liquid-salt coolants. Depending upon goals, the peak coolant operating temperatures are between 700 and 1000°C, with reactor outputs between 2400 and 4000 MW(t). Several fluoride salt coolants that are being evaluated have melting points between 350 and 500°C, values that imply minimum refueling temperatures between 400 and 550°C. At operating conditions, the liquid salts are transparent and have physical properties similar to those of water. A series of refueling studies have been initiated to (1) confirm the viability of refueling, (2) define methods for safe rapid refueling, and (3) aid the selection of the preferred AHTR design. Three reactor cores with different fuel element designs (prismatic, pebble bed, and pin-type fuel assembly) are being evaluated. Each is a liquid-salt-cooled variant of a graphite-moderated high-temperature reactor. The refueling studies examined applicable refueling experience from high-temperature reactors (similar fuel element designs) and sodium-cooled fast reactors (similar plant design with liquid coolant, high temperatures, and low pressures). The findings indicate that refueling is viable, and several approaches have been identified. The study results are described in this paper.

Investigation of High-Temperature Printed Circuit Heat Exchangers for Very High Temperature Reactors

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Sai Mylavarapu ◽  
Xiaodong Sun ◽  
Justin Figley ◽  
Noah Needler ◽  
Richard Christensen
Keyword(s):  
High Temperature ◽  
Heat Exchangers ◽  
Operating Conditions ◽  
Test Facility ◽  
State University ◽  
Printed Circuit ◽  
High Temperature Materials ◽  
System Pressure ◽  
High Temperature Reactors ◽  
Very High

Very high-temperature reactors require high-temperature (900–950°C) and high-integrity heat exchangers with high effectiveness during normal and off-normal conditions. A class of compact heat exchangers, namely, the printed circuit heat exchangers (PCHEs), made of high-temperature materials and found to have these above characteristics, are being increasingly pursued for heavy duty applications. A high-temperature helium test facility, primarily aimed at investigating the heat transfer and pressure drop characteristics of the PCHEs, was designed and is being built at Ohio State University. The test facility was designed to facilitate operation at temperatures and pressures up to 900°C and 3 MPa, respectively. Owing to the high operating conditions, a detailed investigation on various high-temperature materials was carried out to aid in the design of the test facility and the heat exchangers. The study showed that alloys 617 and 230 are the leading candidate materials for high-temperature heat exchangers. Two PCHEs, each having 10 hot plates and 10 cold plates, with 12 channels in each plate, were fabricated from alloy 617 plates and will be tested once the test facility is constructed. Simultaneously, computational fluid dynamics calculations have been performed on a simplified PCHE model, and the results for three flow rate cases of 15, 40, and 80 kg/h at a system pressure of 3 MPa are discussed. In summary, this paper focuses on the study of the high-temperature materials, the design of the helium test facility, the design and fabrication of the PCHEs, and the computational modeling of a simplified PCHE model.

Direct Measurements of the Chromium Activity in Complex Nickel Base Alloys by High Temperature Mass Spectrometry

2008 ◽  
Vol 595-598 ◽  
pp. 975-985 ◽  
Author(s):  
Stéphane Gossé ◽  
Thierry Alpettaz ◽  
Fabien Rouillard ◽  
Sylvie Chatain ◽  
Christine Guéneau ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Temperature ◽  
Surrounding Medium ◽  
Operating Conditions ◽  
Primary Circuit ◽  
Haynes 230 ◽  
Temperature Range ◽  
High Temperature Mass Spectrometry ◽  
Inconel 617 ◽  
Chromium Activity

Chromium rich, nickel based alloys Haynes 230 and Inconel 617 are candidate materials for the primary circuit and intermediate heat exchangers (IHX) of (Very)-High Temperature Reactors. The corrosion resistance of these alloys is strongly related to the reactivity of chromium in the reactor specific environment (high temperature, impure helium). At intermediate temperature – 900°C for Haynes 230 and 850°C for Inconel 617 – the alloys under investigation are likely to develop a chromium-rich surface oxide scale. This layer protects from the exchanges with the surrounding medium and thus prevents against intensive corrosion processes. However at higher temperatures, it was shown that the surface chromia can be reduced by reaction with the carbon from the alloy [1] and the bare material can quickly corrode. Chromium appears to be a key element in this surface scale reactivity. Then, quantitative assessment of the surface requires an accurate knowledge of the chromium activity in the temperature range close to the operating conditions (T ≈ 1273 K). High temperature mass spectrometry (HTMS) coupled to multiple effusion Knudsen cells was successfully used to measure the chromium activity in Inconel 617 and Haynes 230 in the 1423- 1548 K temperature range. Appropriate adjustments of the experimental parameters and in-situ calibration toward pure chromium allow to reach accuracy better than ± 5%. For both alloys, the chromium activities are determined. Our experimental results on Inconel 617 are in disagreement with the data published by Hilpert [2]. Possible explanations for the significant discrepancy are discussed.

Hemispherical Total Emissivity of Potential Structural Materials for Very High Temperature Reactor Systems: Haynes 230

2012 ◽  
Vol 179 (3) ◽  
pp. 429-438 ◽  
Author(s):  
Raymond K. Maynard ◽  
Naphtali M. Mokgalapa ◽  
Tushar K. Ghosh ◽  
Robert V. Tompson ◽  
Dabir S. Viswanath ◽  
...  
Keyword(s):  
High Temperature ◽  
Structural Materials ◽  
Hemispherical Total Emissivity ◽  
Haynes 230 ◽  
Very High Temperature Reactor ◽  
High Temperature Reactor ◽  
Very High ◽  
Total Emissivity

Research on Tensile Properties of Ni-Base Super Alloy GH3128

2016 ◽  
Author(s):  
Xi Zhao ◽  
Yu Zhou ◽  
Kun Yuan
Keyword(s):  
High Temperature ◽  
Tensile Properties ◽  
Heat Exchangers ◽  
Compound Fracture ◽  
Very High Temperature Reactor ◽  
High Temperature Reactor ◽  
Very High ◽  
Super Alloy ◽  
Tension Fracture ◽  
Variation Tendency

GH3128, which is one of the domestic Ni-base super alloy, shows good performances under high temperature. Preliminary research has shown that this alloy is promising as structural material for Intermediate Heat Exchangers (IHX), which are the key components of Very High Temperature Reactor (VHTR). In this paper, the tensile properties of GH3128 are tested by the uniaxial tension experiments, and then the fractographic evaluation is conducted by using the scanning electron microscope (SEM). In the paper, the variation tendency of tensile strengths of GH3128 as well as plasticity is described along with the variation of temperature. The results also show that the tension fracture mode will gradually transform from ductile fracture to cleavage-intergranular compound fracture with the increasing of temperature, and the transition of fracture mechanism corresponds well with the variation of alloy plasticity.

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