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A Brief History of KSOME@

What is 𝕂𝕊𝕆𝕄𝔼?@

𝕂𝕊𝕆𝕄𝔼 (Kinetic Simulations of Microstructural Evolution) is an object kinetic Monte Carlo (OKMC) tool to simulation defect (damage) accumulation in materials under irradiation. 𝕂𝕊𝕆𝕄𝔼 was developed with priority given to the flexibility, ease of upgradability and computational efficiency, in that order. Accordingly, there is no limit on the types of defects or the number of parameters that can be used to capture atomistic details of a defect type. For example, 𝕂𝕊𝕆𝕄𝔼, as expected, can simulate diffusion-reaction processes of a generic self-interstitial atom (SIA) type defect, but it can also explicitly simulate diffusion-reaction processes of an SIA \(\langle 100\rangle\) or SIA \(\langle 111 \rangle\) loops. To read more on 𝕂𝕊𝕆𝕄𝔼'𝕊 capabilities goto the page on the capabilities. 𝕂𝕊𝕆𝕄𝔼 is named after ALSOME (Atomic-Scale Simulations of Microstructural Evolution), which was developed at PNNL in the early 1990s for the same purpose. However, as mentioned earlier, 𝕂𝕊𝕆𝕄𝔼 was developed from the ground up and has no resemblance to the ALSOME code.

𝕂𝕊𝕆𝕄𝔼 was developed to study microstructural evolution in materials under irradiation. Ideation and the development of 𝕂𝕊𝕆𝕄𝔼 was initiated under project titled "Plasma Surface Interactions: Bridging from the Surface to the Micron Frontier through Leadership Computing" jointly funded by the ASCRa and FESb under SciDac3c program. The goal was to use 𝕂𝕊𝕆𝕄𝔼 to study damage accumulation in tungsten due to neutron irradiation. Tungsten is a candidate material for plasma-facing components (PFCs) in a nuclear fusion reactord. The development of 𝕂𝕊𝕆𝕄𝔼 continued under the project titled "Plasma Surface Interactions: Predicting the Performance and Impact of Dynamic PFC Surfaces" also jointly funded by the ASCRb and FESc under SciDac4 program. More details contributes and financial support can be found in the page on acknowledgments

Why a new code?@

With kinetic Monte Carlo (KMC) simulation codes, various processes (more precisely, the diffusion-reaction processes) that can occur in a system were hardwired into the code. The main advantage of explicit hard-wiring of possible processes is the computation efficiency. However, to perform higher fidelity simulations, a significant coding effort is required every time to incorporate either a more accurate description of existing processes or a new process(s). Furthermore, benchmarking is required when such an upgrade results in algorithmic modifications in the execution of previously hardwired processes. As mentioned previously, 𝕂𝕊𝕆𝕄𝔼, was developed with priority given to the flexibility, ease of upgradability and computational efficiency, in that order. The necessity for frequent code upgrades is either eliminated or significantly reduced whenever there is a need to perform higher fidelity simulations. In 𝕂𝕊𝕆𝕄𝔼, the categories of various diffusion-reaction processes and the data-management system are hardwired, while the execution of the diffusion-reaction processes specific to a system is specified via input files. In the present version of 𝕂𝕊𝕆𝕄𝔼, the analytical expression required to calculate defect interaction radii are inputted via a text file. However, the ability to parse mathematical expressions from a text file can be extended to input the analytical expression to calculate other defect properties, including the expressions to calculate the change in the migration barriers of mobile defects due to long-range interaction with extended defects.

Publications & Reports Using 𝕂𝕊𝕆𝕄𝔼@

Journal Publications@

  1. G. Nandipati, W. Setyawan,H. L. Heinisch, K. J. Roche, R. J. Kurtz, and B. D. Wirth,โ€œDisplacement Cascades and Defects Annealing in tungsten, Part II: Object kinetic Monte Carlo Simulation of Tungsten Cascade Agingโ€ J. Nucl Mater. 462, 338-344 (2015)
  2. G. Nandipati, W. Setyawan, H. L. Heinisch, K. J. Roche, R. J. Kurtz, and B. D. Wirth,โ€œDisplacement Cascades and Defects Annealing in tungsten, Part III: Sensitivity of Cascade Annealing in tungsten on kinetic parametersโ€ J. Nucl Mater. 462, 345-353 (2015)
  3. G. Nandipati, W. Setyawan, K. J. Roche, R. J. Kurtz, and B. D. Wirth,โ€œEffect of confinement of SIA cluster diffusion by impurities on radiation defect accumulation due to 14 MeV neutrons in tungstenโ€ J. Nucl Mater. 542, 152402 (2020)
  4. G. Nandipati, K. D. Hammond, D. Maroudas, K. J. Roche, R. J. Kurtz, B. D. Wirth, W. Setyawan Effect of Helium Flux on Nearโ€Surface Helium Accumulation in Plasmaโ€exposed Tungsten, J. Phys: Condens. Matter 34, 035701 (2021)

Reports@

  1. G. Nandipati W. Setyawan, K. J. Roche, R. J. Kurtz and B. D. Wirth, โ€œObject Kinetic Monte Carlo Simulation of Radiation Damage Accumulation in Tungstenโ€ DOE/ER-0313/59-Vol 60 Semiannual Progress Report June 30, 2016 pp. 178-182.

  2. G. Nandipati A. Pattanayak, W. Setyawan, R. J. Kurtz, A. Selby and B. D. Wirth, โ€œOKMC Study of Comparison of Cascade Annealing in Tungsten, Molybdenum and Chromiumโ€ DOE/ER-0313/61-Vol 61 Semiannual Progress Report Dec 31, 2016 pp. 120-121

  3. G. Nandipati, W. Setyawan, H. L. Heinisch, K. J. Roche, R. J. Kurtz, and B. D. Wirth, โ€œObject kinetic Monte Carlo Simulation of Radiation Damage in Tungstenโ€ DOE/ER-0313/58-Vol 58 Semiannual Progress Report June, 2015 pp. 262-265.
  4. G. Nandipati, W. Setyawan, K. J. Roche, R. J. Kurtz and B. D. Wirth, โ€œObject Kinetic Monte Carlo Simulations Of Radiation Damage In Tungsten Subjected To Neutron Flux With PKA Spectrum Corresponding To HFIRโ€ DOE/ER-0313/59-Vol 59 Semiannual Progress Report Dec 31, 2015 pp. 126-129.
  5. G. Nandipati, W. Setyawan, H. L. Heinisch, K. J. Roche and R. J. Kurtz, and B. D. Wirth, โ€œImplementation of firstโ€‘passage time approach for object kinetic Monte Carlo simulation of irradiationโ€ DOE/ER-0313/56-Vol56 Semiannual Progress Report June 30, 2014 pp. 213-216.
  6. G. Nandipati, W. Setyawan, H. L. Heinisch, K. J. Roche, R. J. Kurtz, and B. D. Wirth, โ€œObject kinetic Monte Carlo Simulation of Radiation Damage in Tungstenโ€ DOE/ER-0313/57-Vol57 Semiannual Progress Report Dec, 2014 pp. 160-165.
  7. G. Nandipati, W. Setyawan, H. L. Heinisch, K. J. Roche, R. J. Kurtz, and B. D. Wirth, โ€œObject Kinetic Monte Carlo simulations of microstructure evolutionโ€ DOE/ER-0313/54 - Vol 54 Semiannual Progress Report June 30, 2013 pp. 179-183.
  8. G. Nandipati, W. Setyawan, H. L. Heinisch, K. J. Roche, R. J. Kurtz, and B. D. Wirth, โ€œObject Kinetic Monte Carlo simulations of cascade aging in Tungstenโ€ DOE/ER-0313/54-Vol 55 Semiannual Progress Report Dec 31, 2013 pp. 161-166.

a ASCR: Advanced Scientific Computing Research
b FES: Office of Fusion Energy Sciences
c SciDac: Scientific Discovery through Advanced Computing
d For more information on nuclear fusion reactors go to home page of International Thermonuclear Experimental Reactor (ITER)

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