James Wall

• Electric Power Research Institute

Time-of-flight neutron diffraction and energy-resolved imaging each provide unique perspectives into material properties. Neutron diffraction is useful for assessing microstructural parameters such as phase composition, texture, and dislocation densities, though it typically provides averaged data over the sampled volume. Energy-resolved imaging, o...

The US code of Federal Regulations mandates regular inspection of centrifugally cast austenitic stainless steel pipe, commonly used in primary cooling loops in light-water nuclear power plants. These pipes typically have a wall thickness of ~8 cm. Unfortunately, inspection using conventional ultrasonic techniques is not reliable as the microstructu...

This research combines linear and nonlinear ultrasound to examine the microstructural and microchemical changes in five large, highly irradiated cold-worked ANSI 304 stainless steel coin specimens cut from two hexagonal cross section blocks with radiation damage levels ranging from ~0.4 to ~33 dpa following irradiation in the EBR-II fast reactor. B...

This research combines linear and nonlinear ultrasound to examine the microstructural and microchemical changes in five large, highly irradiated cold-worked ANSI 304 stainless steel coin specimens cut from two hexagonal cross section blocks with radiation damage levels ranging from ~0.4 to ~33 dpa following irradiation in the EBR-II fast reactor. B...

This paper reports on the first successful nonlinear ultrasonic measurement on highly irradiated specimens in a hot cell environment. The specimens are ANSI 304 stainless steel specimens for which the microstructure characterization and ultrasonic velocity measurement have been previously conducted. The critical part of this research is the develop...

This research explores the sensitivity of nonlinear ultrasound (NLU) to the changes in microstructure of heat treated Fe-1.0 at.% Cu binary alloy. Results from experimental measurements and a theoretical model each show that the acoustic nonlinearity parameter, β increases with increasing Cu-precipitate radius. The iron-copper material investigated...

Austenitic stainless steels have a wide range of applications in the energy industry, but the corrosion resistance of these stainless steels can be reduced by sensitization, particularly in the heat affected zones in welds. Sensitization is the formation of chromium carbide precipitates along the grain boundaries, causing the formation of a zone of...

Nonlinear ultrasound (NLU) has been shown to be sensitive to microstructural features including precipitates and dislocations. The heat-affected zone (HAZ) of welded austenitic stainless steels can be susceptible to intergranular stress corrosion cracking (IGSCC). This research uses NLU to evaluate the microstructure of the HAZ with an emphasis on...

A review of the current state of knowledge on the effects of radiation on concrete in nuclear power production applications is presented. Emphasis is placed on the effects of radiation damage, as reflected by changes in engineering properties of concrete, in the evaluation of the long-term operation and for plant life or aging management of nuclear...

License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has resulted in a renewed focus on long-term aging of materials at nuclear power plants (NPPs) including concrete. Large irreplaceable sections of most nuclear generating stations include concrete. The Expanded Materials Degradation Analysis, jointly perfor...

This research uses nonlinear Rayleigh surface waves to characterize stress corrosion cracking (SCC) damage in welded 304 Stainless Steel (304 SS). 304 SS is widely used in reactor pressure vessels, where a corrosive environment in combination with applied stress due to high internal pressures can cause SCC. Welds and the nearby heat affected zones...

Material damage in structural components is driven by microstructural evolution that occurs at low length scales and begins early in component life. In metals, these microstructural features are known to cause measurable changes in the acoustic nonlinearity parameter. Physically, the interaction of a monochromatic ultrasonic wave with microstructu...

Dommages d’irradiation du béton des puits de cuve des réacteurs T.M. Rosseel1, J.J. Wall2, K.G. Field1, Y. Le Pape1*, D.J. Naus1, I. Remec1, J.T. Busby1, P. Bruck3 1 Oak Ridge National Laboratory 2 Electric Power Research Institute 3 LPI, Inc. Le prolongement de la durée de fonctionnement des réacteurs au-delà de 60 ans et l’amélioration de leur p...

Radiation damage occurs in reactor pressure vessel (RPV) steel, causing microstructural changes such as point defect clusters, changes in dislocation density, and precipitates. These radiation-induced microstructural changes cause material embrittlement. Radiation damage is a crucial concern in the nuclear industry because many nuclear plants throu...

This research is part of a broader effort to develop a nondestructive evaluation technique to monitor radiation damage in reactor pressure vessel steels, the main contributor being copper-rich precipitates. In this work, 17-4PH stainless steel is thermally aged to study the effects of copper precipitates on the acoustic nonlinearity parameter. Nonl...

The stress exponent in the power-law creep of niobium at 1985 °C was measured by a non-contact technique using an electrostatic levitation facility at NASA MSFC. This method employs a distribution of stress to allow the stress exponent to be determined from each test, rather than from the curve fit through measurements from multiple samples that is...

Current nondestructive examination (NDE) technology detection capabilities limit our ability to detect stress corrosion cracking (SCC) damage until it has progressed significantly. This work describes the continued development of an in-situ monitoring technique to detect and characterize mechanical damage caused by SCC, allowing the detection of th...

Nuclear generation currently accounts for roughly 20% of the US baseload power generation. Yet, many US nuclear plants are entering their first period of life extension and older plants are currently undergoing assessment of technical basis to operate beyond 60 years. This means that critical components, such as the reactor pressure vessel (RPV), w...

Nonlinear ultrasonic waves have shown to be sensitive to various microstructural changes in metals including coherent precipitates; these precipitates introduce a strain field in the lattice structure. The thermal aging of certain alloy steels leads to the formation of coherent precipitates, which pin dislocations and contribute to the generation...

Nuclear generation currently accounts for roughly 20% of the US baseload power generation. Yet, many US nuclear plants are entering their first period of life extension and older plants are currently undergoing assessment of technical basis to operate beyond 60 years. This means that critical components, such as the reactor pressure vessel (RPV), w...

Radiation Damage In Reactor Cavity Concrete T.M. Rosseel1, J.J. Wall2, K.G. Field1, Y. Le Pape1*, D.J. Naus1, I. Remec1, J.T. Busby1, and P. Bruck3 1 Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, TN 37831-6148 2 Electric Power Research Institute, 1300 W W.T. Harris Blvd, Charlotte, NC 28262 3LPI, Inc. 36 Main Street, Amesbury,...

Current nondestructive examination (NDE) technology detection capabilities limit our ability to detect stress corrosion cracking (SCC) damage until it has progressed significantly. This work describes the continued development of an in-situ monitoring technique to detect and characterize mechanical damage caused by SCC, allowing the detection of th...

This work demonstrates how nonlinear ultrasound (NLU) can be used to monitor radiation damage in nuclear reactor pressure vessel (RPV) steels. Radiation damage is a crucial concern in the nuclear industry since many nuclear plants throughout the United States are entering a period of life extension, meaning the RPV will be exposed to higher levels...

To ensure the long and safe operation of power plants, structural parts must be monitored for damage. In the case of welded steel pipes that maintain high pressures in high temperature environments, a common cause of failure is creep damage. Severe creep damage often occurs in the heat affected zone (HAZ). Previous research has shown that nonlinear...

Nonlinear ultrasound was used to monitor radiation damage in two reactor pressure vessel (RPV) steels. The microstructural changes associated with radiation damage include changes in dislocation density and the formation of precipitates, and nonlinear ultrasonic waves are known to be sensitive to such changes. Six samples each of two different RPV...

In-situ, time-of-flight neutron diffraction was performed to investigate the martensitic phase transformation during quasi-static uniaxial compression testing of 304L stainless steel at 300K (room temperature) and 203K. In-situ neutron diffraction study enabled the bulk measurement of intensity evolution for each hkl atomic plane during the austeni...

a b s t r a c t Neutron and synchrotron X-ray diffractions were used to study the texture development in the face-centered-cubic nickel-based superalloy over gauge volumes ranging from hundreds of cubic millimeters down to sub-cubic micrometers. The bulk averaged results find a uniform texture development from collective slip. However, X-ray microb...

The metallic glass-forming alloy VIT-105 (Zr52.5Cu17.9Ni14.6Al10Ti5) was used to study the effect of oxygen on nucleation. Ex situ synchrotron X-ray scattering experiments performed on as-cast samples showed that oxygen leads to the formation of tetragonal and/or cubic phases, depending on oxygen content. The samples crystallized into either a prim...

A combined X-ray diffraction, EELS and DFT study of the reaction of rhenium with carbon at high-(P, T) conditions up to Pmax = 67 GPa and T max = 3800 K is presented. A hexagonal rhenium carbide, ReC x, was identified as the stable phase at high-(P, T) conditions. A composition of ReC0.5 is proposed. No evidence for a cubic ReC polymorph with rocks...

Nucleation in the undercooled liquid state in the bulk metallic glass-forming composition Zr52.5Cu17.9Ni14.6Al10Ti5 (VIT-105), produced using high purity (PA) and commercial purity (CA) raw materials was investigated using electrostatic levitation and ex situ neutron diffraction. The CA material was observed to have a lower density than the PA samp...

Zr52.5Cu17.9Ni14.6Al10Ti5 was doped with oxygen and erbium to determine the effect of impurity oxygen and microalloying on the stability of the liquid during processing from the melt. It was established that oxygen concentrations of 5000–14,000ppm (atomic herein) destabilized the alloy significantly, consistent with data trends seen in the literatu...

We investigate the residual strains in a free-standing Cu/Nb multilayer of 30 nm nominal layer thickness with synchrotron x-rays. This material system is characterized by columnar grains of Cu and Nb with incoherent interfaces and a sharp physical-vapor-deposition texture. High energy x-rays were used with an area detector along with multiple sampl...

Continuing pressures for higher performance and efficiency in energy conversion and propulsion systems are driving ever more demanding needs for new materials which can survive high stresses at the elevated temperatures. In such severe environments, the characterization of creep properties becomes indispensable. Conventional techniques for the meas...

Containerless aerodynamic levitation was used to produce the bulk metallic glass Zr57Ti5Ni8CU20Al10. Samples were processed from the liquid state at cooling rates in the range of 69-1.2 K/s. The alloy was found to vitrify at cooling rates from 69 to 11 K/s and recalesced at the slower cooling rates. X-ray diffraction confirmed that the specimens pr...

In situ time-of-flight neutron diffraction was performed to investigate the martensitic phase transformation during quasistatic uniaxial compression testing of 304L stainless steel at 300 and 203 K. In situ neutron diffraction enabled the bulk measurement of intensity evolution for various hkl atomic planes during the austenite (fcc) to martensite...

Based on a systematic study of pair distribution functions, carried out at cryogenic and ambient temperatures, on as-cast and crystallized ternary Zr-based bulk amorphous alloys (BAAs), we found that the atoms in BAAs are inhomogenously distributed at a local atomic level. They exist as different clusters with significantly shorter bond lengths tha...

The development of a machine with the capability to manufacture bulk-amorphous metal-alloy castings with a wide range of geometries and dimensions is described. The design utilizes a method of melting and alloying elemental metals and subsequently quench casting while controlling relative pressures to facilitate both drop and suction castings withi...

Volume averaged thermal residual stresses in a TiC–50 vol.% Ni3Al cermet were measured over a temperature range from room temperature to about l250 K using in situ neutron diffraction. At room temperature, the thermal residual stresses in both the Ni3Al binder and the TiC particles were about 1.6 GPa. In the temperature range studied, the residual...

Combustion synthesis (CS) is a low-energy processing approach for a wide range of materials (e.g. ceramics, intermetallics and composites), whereby reactants are ignited to spontaneously transform to products in an exothermic reaction. The process can be subdivided into two modes of ignition. The first is termed self-propagating high temperature sy...

This paper presents a new low-energy method for forging intermetallics during the high temperatures achieved in reaction synthesis from elemental powders. Iron aluminide (FeAl) was successfully forged at considerably lower operating temperatures than conventionally used. The advantages and potential of the approach are discussed.

Intermetallic materials have long attracted the serious attention of scientific and industrial organizations. This is primarily due to their attractive properties, which include high-temperature oxidation and corrosion resistance, low density, and high-temperature strength. Major drawbacks that have so far restricted the application of such materia...