Ramprashad Prabhakaran

Profile Information
Mr. Ramprashad Prabhakaran
Pacific Northwest National Laboratory
Pacific Northwest National Laboratory
Advanced Fuels, Friction Stir Welding, Fuel Cladding, Irradiation Damage Behavior, Mechanical Properties, Small-Scale Mechanical Testing
"Ion irradiation and examination of Additive friction stir deposited 316 stainless steel" Priyanka Agrawal, Ching-Heng Shiau, Aishani Sharma, Zhihan Hu, Megha Dubey, Yu Lu, Lin Shao, Ramprashad Prabhakaran, Yaqiao Wu, Rajiv Mishra, Materials & Design Vol. 238 2024 112730 Link
This study explored solid-state additive friction stir deposition (AFSD) as a modular manufacturing technology, with the aim of enabling a more rapid and streamlined on-site fabrication process for large meter-scale nuclear structural components with fully dense parts. Austenitic 316 stainless steel (SS) is an excellent candidate to demonstrate AFSD, as it is a commonly-used structural material for nuclear applications. The microstructural evolution and concomitant changes in mechanical properties after 5 MeV Fe++ ion irradiation were studied comprehensively via transmission electron microscopy and nanoindentation. AFSD-processed 316 SS led to a fine-grained and ultrafine-grained microstructure that resulted in a simultaneous increase in strength, ductility, toughness, irradiation resistance, and corrosion resistance. The AFSD samples did not exhibit voids even at 100 dpa dose at 600 °C. The enhanced radiation tolerance as compared to conventional SS was reasoned to be due to the high density of grain boundaries that act as irradiation-induced defect sinks.
"Thermomechanical Properties of Neutron Irradiated Al3Hf-Al Thermal Neutron Absorber Materials" Donna Guillen, Mychailo Toloczko, Ramprashad Prabhakaran, Yuanyuan Zhu, Yu Lu, Yaqiao Wu, Materials Vol. 16 2023 5518 Link
thermal neutron absorber material composed of Al3Hf particles in an aluminum matrix is under development for the Advanced Test Reactor. This metal matrix composite was fabricated via hot pressing of high-purity aluminum and micrometer-size Al3Hf powders at volume fractions of 20.0, 28.4, and 36.5%. Room temperature tensile and hardness testing of unirradiated specimens revealed a linear relationship between volume fraction and strength, while the tensile data showed a strong decrease in elongation between the 20 and 36.5% volume fraction materials. Tensile tests conducted at 200 °C on unirradiated material revealed similar trends. Evaluations were then conducted on specimens irradiated at 66 to 75 °C to four dose levels ranging from approximately 1 to 4 dpa. Tensile properties exhibited the typical increase in strength and decrease in ductility with dose that are common for metallic materials irradiated at ≤0.4Tm. Hardness also increased with neutron dose. The difference in strength between the three different volume fraction materials was roughly constant as the dose increased. Nanoindentation measurements of Al3Hf particles in the 28.4 vol% material showed the expected trend of increased hardness with irradiation dose. Transmission electron microscopy revealed oxygen at the interface between the Al3Hf particles and aluminum matrix in the irradiated material. Scanning electron microscopy of the exterior surface of tensile tested specimens revealed that deformation of the material occurs via plastic deformation of the Al matrix, cracking of the Al3Hf particles, and to a lesser extent, tearing of the matrix away from the particles. The fracture surface of an irradiated 28.4 vol% specimen showed failure by brittle fracture in the particles and ductile tearing of the aluminum matrix with no loss of cohesion between the particles and matrix. The coefficient of thermal expansion decreased upon irradiation, with a maximum change of −6.3% for the annealed irradiated 36.5 vol% specimen.
"“Microstructure and mechanical properties of friction stir welded MA956" Ramprashad Prabhakaran, TMS 2009 Annual Meeting February 15-17, (2009)
"Friction stir welding of MA956 and MA754 ODS alloys" Ramprashad Prabhakaran, Materials science & technology (MS&T) 2010 October 17-21, (2010)
"Friction stir welding of oxide dispersion strengthened alloys" Ramprashad Prabhakaran, ANS 2010 annual meeting (NFSM) June 13-17, (2010)
"Irradiation studies on friction stir welded MA956 and MA754" Ramprashad Prabhakaran, TMS 2012 annual meeting March 11-15, (2012)
"Irradiation studies on friction stir welded ODS alloys" Ramprashad Prabhakaran, TMS 2013 Annual Meeting March 3-7, (2013)
"Microstructural and mechanical characteristics of friction stir welded ODS alloys" Ramprashad Prabhakaran, 2010 TMS Annual Meeting February 14-18, (2010)
"Microstructure and mechanical properties of friction stir welded MA956 and MA754" Ramprashad Prabhakaran, MS&T 2009 October 25-29, (2009)
"Microstructure and mechanical properties of irradiated friction stir welded ODS alloys" Ramprashad Prabhakaran, TMS 2011 annual meeting February 27-3, (2011)
"Small-scale specimen testing of irradiated MA 754 and MA 957 alloys" Ramprashad Prabhakaran, MS&T 2008 October 5-9, (2008)
"The effect of neutron irradiation on friction stir welded MA956 and MA754" Ramprashad Prabhakaran, Materials Science & Technology (MS&T) October 7-11, (2012)
NSUF Articles:
U.S. DOE Nuclear Science User Facilities Awards 30 Rapid Turnaround Experiment Research Proposals - Awards total nearly $1.2 million The U.S. Department of Energy (DOE) Nuclear Science User Facilities (NSUF) has selected 30 new Rapid Turnaround Experiment (RTE) projects, totaling up to approximately $1.2 million. These projects will continue to advance the understanding of irradiation effects in nuclear fuels and materials in support of the mission of the DOE Office of Nuclear Energy. Wednesday, April 26, 2017 - Calls and Awards
RTE 1st Call Awards Announced - Projects total approximately $1.4 million These projects will continue to advance the understanding of irradiation effects in nuclear fuels and materials in support of the mission of the DOE-NE. Friday, February 8, 2019 - Calls and Awards
DOE awards 39 RTE Projects - Projects total approximately $1.3 million Thursday, February 1, 2018 - Calls and Awards
DOE Awards 31 RTE Proposals, Opens FY-20 1st Call - Projects total $1.1 million; Next proposals due 10/31 Awards will go to 22 principal investigators from universities, six from national laboratories, and three from foreign universities. Tuesday, September 17, 2019 - Calls and Awards, Announcement
Users Organization Meeting Presentations Now Available - Wednesday, March 25, 2020 - Newsletter, Users Group
DOE Awards Eight CINR NSUF Projects - Projects include $3M in access grants and R&D funding Monday, July 6, 2020 - Calls and Awards
Department of Energy Nuclear Science User Facilities Awards 29 Rapid Turnaround Experiment Proposals - Awarded projects total nearly $1.14M in access awards Tuesday, June 8, 2021 - News Release, Calls and Awards
U.S. Department of Energy Announces FY21 CINR Awards - DOE has selected 4 NSUF projects U.S. Department of Energy (DOE) selected four projects that will take advantage of Nuclear Science User Facilities (NSUF) capabilities to investigate important nuclear fuel and material applications. Monday, June 28, 2021 - Calls and Awards
NSUF awards 28 Rapid Turnaround Experiment proposals - Approximately $1.74M has been awarded. The new call closes June 28. Thursday, June 1, 2023 - Calls and Awards
NSUF welcomes 2024 Users Organization Executive Committee - Tuesday, February 6, 2024 - Users Group
NSUF Research Collaborations

Effect of ion irradiation and dose rates on 316LY oxide-dispersion-strengthened steel additively manufactured by laser-directed energy deposition - FY 2023 RTE 2nd Call, #4723

Effect of neutron irradiation on the microstructure of NF616 (Grade 92) as a function of dose and temperature - FY 2022 RTE 1st Call, #4453

Elemental effects on radiation damage in tempered martensitic steels neutron irradiated to high doses at fast reactor relevant temperatures - FY 2024 CINR, #5020

Influence of Fast Neutron Irradiation on the Mechanical Properties and Microstructure of Nanostructured Metals/Alloys - FY 2008 Call for User Proposals, #96

Ion Irradiation and Characterization of FeCrAl Oxide Dispersion Strengthend Alloy Manufactured via Laser Powder Bed Fusion - FY 2022 RTE 1st Call, #4400

Ion Irradiation and examination of 304 Stainless Steel and 304 ODS Steel Additively Manufactured via Selective Laser Melting - FY 2021 RTE 1st Call, #4352

Ion Irradiation and Examination of Additive Friction Stir Manufactured 316 Stainless Steel Component - FY 2021 RTE 1st Call, #4307

Ion irradiation and examination of metastability engineered stainless high entropy alloy - FY 2020 RTE 2nd Call, #4112

Microstructural characterization of neutron irradiated HT-9 heats (ORNL, LANL and EBR II) at LWR and fast reactor relevant temperatures - FY 2020 RTE 2nd Call, #4201

Room Temperature Tensile Properties of ATR Neutron Irradiated T91 - FY 2023 RTE 2nd Call, #4705

TEM characterization of neutron irradiated HT-9 as a function of irradiation temperature and dose - FY 2024 RTE 2nd Call, #4945