T.P. Diaz

National Synchrotron Radiation Research Center

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Samson Hettiarachchi

Hitachi Global Storage Technologies (United States)

G.P. Wozadlo

General Electric (United States)

S. Hettiarachchi

London South Bank University

W.D. Miller

General Electric (Israel)

N.R. Hughes

General Electric (United States)

Robert L. Cowan

Lawrence Livermore National Security

R. J. Law

Science Museum

R. L. Cowan

DVGW-Forschungsstelle am Engler-Bunte-Institut des Karlsruher Instituts für Technologie

V. V. Pestanas

General Electric (United States)

Peter L. Andresen

Shanghai Jiao Tong University

Cooperative Institutions

General Electric (United States)

General Electric (Israel)

Electric Power Research Institute

Benemérita Universidad Autónoma de Puebla

Universidad Nacional Autónoma de México

National Synchrotron Radiation Research Center

General Electric (Germany)

Structural Integrity Associates (United States)

Idaho National Laboratory

Pennsylvania State University

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The concept of noble metal chemical addition technology for IGSCC mitigation of structural materials

S. Hettiarachchi G.P. Wozadlo Peter L. Andresen T.P. Diaz R. L. Cowan

Hydrogen Water Chemistry (HWC) has been successfully employed to mitigate the IGSCC of BWR components in the recent years. However, to mitigate SCC in some vessel internals requires the use of high levels of feed water hydrogen, which results in high main steam radiation dose rate increases. Recent studies have shown that the presence of noble metals on these surfaces, by alloying or surface deposition by plating or various thermal spray coating techniques significantly reduced the hydrogen demand necessary to achieve the IGSCC protection potential of {minus}0.230 V(SHE). These techniques, although attractive, have some limitations because accessibility to individual components is a requirement for their successful application. This paper describes the concept of a novel method of applying noble metals potentially to all in-core wetted components by employing the reactor coolant water as the medium of transport for depositing noble metal on in-core metal surfaces. The concept of noble metal chemical addition (NMCA) technology has been successfully used in numerous laboratory tests to create a ``noble metal like`` (catalytic) surface on four of the major structural materials, Type 304 SS, Inconel 600, Alloy 182 weld metal and low alloy steel. The success of this technology has been tested using constantmore » extension rate tensile (CERT) tests, crack growth rate (CGR) tests and electrochemical corrosion potential (ECP) response tests. The NMCA technology has successfully decreased the ECP of surfaces below {minus}0.230 V(SHE), prevented crack initiation and mitigated crack growth rates in stoichiometric excess hydrogen in simulated boiling water reactor (BWR) environments, even at high oxygen or hydrogen peroxide levels. The NMCA treatment of surfaces has minimized the hydrogen demand necessary for IGSCC protection of the materials tested. Tests are in progress to qualify this process for operating BWRs.« less

Noble metal

Inconel 625

Inconel

Boiling water reactor

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Effect of flow velocity on crack initiation

Samson Hettiarachchi G.P. Wozadlo T.P. Diaz K.S. Ramp John E. Weber

Constant extension rate tensile (CERT) tests are traditionally used to understand the influence of material composition, heat treatment, temperature and environmental variables on stress corrosion crack (SCC) initiation. However, fluid flow rate has not been investigated as a parameter that could affect SCC initiation until recently. These studies have exhibited longer time to failure under high flow conditions indicating delayed crack initiation. Because these experiments have been performed in highly oxygenated water, no correlation has been established between the influence of flow velocity on the electrochemical corrosion potential (ECP) and the time to failure of tensile test specimens. The interrelationship between the fluid flow velocity, ECP and the time to failure is of great interest to the Boiling Water Reactor (BWR) applications primarily because of the previous observations that the ECP of Type 304 stainless steel increases with fluid flow velocity. This paper describes an attempt that has been made to understand the interrelationship between fluid flow velocity, ECP and the time for crack initiation in high temperature high purity water simulating both the BWR chemistry and the component flow velocity conditions. The range of flow velocities employed in the present study was 0.002 to 2 ft/s. The studies indicatemore » that while high flow velocities can increase ECP there is a delayed effect on crack initiation.« less

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Prediction of environmentally assisted crack growth in a large diameter stainless steel pipe

S. Ranganath A.E. Pickett Gary L. Stevens T.P. Diaz D. Weinstein

Analytical models are being used to predict intergranular stress corrosion crack growth (IGSCC) in austenitic components. An important feature of these models is the ability to separately consider the effect of key material and water chemistry parameters, such as sensitization, conductivity, and electrochemical potential (ECP). The validation of these models has been based primarily on comparison with small specimen data, such as compact tension tests under sustained loading. Before the models can be used to predict crack growth in power plant piping, it is necessary to benchmark the analysis with experimental data on stress corrosion cracks in piping welds with loading similar to that expected in an operating plant. This paper describes the results from testing a 10-inch diameter stainless steel pipe having real and simulated cracks in the weld heat affected zone (HAZ).

Austenitic stainless steel

Tension (geology)

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Chemical preparation of GaAs (100), (110), (111) and (112) substrates with HF:H₂O₂: citric acid:H₂O

Acta Crystallographica Section A Foundations of Crystallography (2005)

T.P. Diaz A. Alvarado E. Rosendo H. Juárez Graciela Ruth Delgadillo García

AND THIN FILMS C410 depth profile the surface disorder and possible pressure induced phase transitions.The results indicate that all of the studied compounds were changed due to the compression.The GID analysis shows that the surface regions of the compacted tolbutamide, carbamazepine and chlorpropamide tablets were disordered.The manifestations of the disordering in the diffractographs are the increased peak intensity and height and the decreased peak width.Moreover, a polymorphic phase transition was observed in chlorpropamide tablets.The biggest changes took place at the very surface of the tablets.The transitions were also dependent on the used compaction pressure.

10.1107/s0108767305082656

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Resolving Electrocatalytic SCC Mitigation Issues in High Temperature Water

CORROSION (2004)

Peter L. Andresen T.P. Diaz Samson Hettiarachchi

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Qualification of Induction Heating Stress Improvement for Mitigation of Stress Corrosion Cracking

Journal of Pressure Vessel Technology (1982)

N.R. Hughes T.P. Diaz V. V. Pestanas

This paper describes the efforts toward qualification of induction heating stress improvement (IHSI) for mitigation of intergranular stress corrosion cracking (IGSCC) in Boiling Water Reactor (BWR) piping. The IHSI process, which is applied to piping after it is fully erected, produces compressive residual stresses on the pipe inside surface in the vicinity of the weld heat affected zone (HAZ). The creation of these compressive stresses has been confirmed by surface and through-wall strain gage and X-ray diffraction residual stress measurements on 4, 10, and 16-in. dia Schedule 80 welded and IHSI treated pipes. Confirmation of increased resistance to IGSCC due to the IHSI process has been accomplished by full-sized 4-in-dia pipe tests in General Electric’s Pipe Test Laboratory. The pipe test utilized an environment of oxygenated high-purity water at 288°C (550°F). Axial loads were applied which exceeded the material 288°C yield strength.

10.1115/1.3264227

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Evaluation of recent experience using zinc addition to reduce BWR primary system radiation buildup

W.J. Marble T.P. Diaz Howard A. Levin Susan Garcia

This report provides the status of zinc addition to the boiling water reactor (BVM) for the purpose of controlling shutdown dose rates in the primary system. For the thirteen plants which have reported results thus far, the most recent average contact dose rate at the standard comparison locations is 135 mR/h. The historical averages at these locations in non-zinc BWRs has been approximately 350 mR/h. The other impacts of zinc additions on BWR chemistry, fuel performance and IGSCC mitigation are discussed. The report concludes that the use of zinc addition has successfully lowered dose rates and recommends broader industry implementation.

Shut down

Boiling water reactor

Dose rate

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Application of Noble Metal Chemical Addition Technology to an Operating BWR to Mitigate IGSCC of Reactor Internals

Samson Hettiarachchi R. J. Law T.P. Diaz W.D. Miller Robert L. Cowan

Hydrogen Water Chemistry (HWC) has been successfully employed to mitigate the IGSCC of BWR internals over the past decade. However, the use of elevated levels of feed water hydrogen in the BWR results in high operating dose rates due to N{sup 16} partitioning into the main steam. Recent studies have shown that the presence of noble metals on reactor internal surfaces, by alloying or by various spray techniques could significantly reduce the hydrogen demand necessary to achieve the IGSCC protection potential of {minus}230 mV(SHE) without the operating dose rate increase. A simpler method of applying noble metal on to reactor internals involve the addition of a noble metal compound into reactor water to cause deposition of noble metal from solution onto surfaces. This noble metal chemical addition (NMCA) technology has been successfully used in numerous laboratory tests to produce a ``noble metal like`` surface on three of the major structural materials, Type 304 SS, Inconel 600 and Alloy 182, used in the nuclear industry. The success of this technology has been tested using constant extension rate tensile (CERT) tests, crack growth rate (CGR) tests and electrochemical corrosion potential (ECP) response tests. The NMCA technology has successfully decreased the ECP ofmore » surfaces below {minus}230 mV{sub SHE}, prevented crack initiation and mitigated crack growth rates in stoichiometric excess hydrogen in simulated boiling water reactor (BWR) environments. The NMCA treatment of surfaces has drastically lowered the hydrogen demand necessary for IGSCC protection of the materials tested, with no identified side effects including no adverse effects on zircaloy fuel cladding materials. This paper describes the performance of the first NMCA treated BWR over a 12 month period. The paper will also describe the application of NMCA technology to internal components of the BWR by employing the reactor coolant water as the medium of transport for depositing noble metal on in-reactor surfaces. The paper will also describe results obtained during the process application, the plant response to low hydrogen after NMCA treatment and the plant performance in maintaining low ECPS during the fuel cycle. The benefits of the application of NMCA technology to the operating BWR fleet will also be highlighted.« less

Noble metal

Boiling water reactor

Inconel

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Sodium-heated steam generator model tests at SGTR. Volume 1. Test rig operating experience and cleaning, disassembly, and inspection of the steam generator test models.

Jack M. Scott Joseph Sam Armijo George J. Licina T.P. Diaz G. Gaul

10.2172/4532703

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Long-Term Performance of Noble Metal Doped Surfaces in Simulated BWR Environments

Samson Hettiarachchi G.P. Wozadlo T.P. Diaz

Noble metal

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