NSUF 19-1767: Density Functional Theory Study of Defects, Solubility of Fission Products and Pu, and Phase Separation in U3Si2 Nuclear Fuel
In recent year, there has been considerable interest in the possibility of replacing currently used UO2 fuel in commercial light water reactors (LWRs) with U3Si2. However, unlike UO2, the lack of essential knowledge of the thermo-mechanical properties of U3Si2, especially under irradiation, is a hindrance to its licensing for use as a nuclear fuel in commercial LWRs. We direct our attention to studying the behavior of fission products and their phases in the U3Si2 fuel, and the radiation-induced defects using first-principles calculations. We are going to calculate the solubility of fission products Mo, Zr, Ce, Ru, Pr, Y, Gd, Ba in the U3Si2 fuel, as well as the transuranic Pu, by calculating the energies for forming various defects in a U3Si2 supercell. Additionally, from the induced volume variation of the U3Si2 supercell, we can determine the effect of the fission product or Pu on the swelling of U3Si2. The calculated total energies of supercells with defects will be further used for analyzing the mixing energies, which will give information on whether a more stable secondary fission product or Pu phase can precipitate in U3Si2 fuel matrix. Lastly, to gain insight into the radiation damage and recovery from radiation damage in U3Si2, we are going to calculate the energies for forming Frenkel pairs and Schottky defects. For this study, we are going to use the DFT+U method, with a U-value of 1.5 eV for the uranium and plutonium atoms, and 2x2x3 supercell of the U3Si2 primitive cell. We are going to consider three substitutional defects (U1, U2, and Si), four interstitial sites, and Frenkel pairs and Schottky defects at three different distances. Because for calculating the defect formation and mixing energies the total energies of the fission products and Pu phases are required, we are also going to relax their binary and ternary phases.
Additional Info
| Field | Value |
|---|---|
| Abstract | In recent year, there has been considerable interest in the possibility of replacing currently used UO2 fuel in commercial light water reactors (LWRs) with U3Si2. However, unlike UO2, the lack of essential knowledge of the thermo-mechanical properties of U3Si2, especially under irradiation, is a hindrance to its licensing for use as a nuclear fuel in commercial LWRs. We direct our attention to studying the behavior of fission products and their phases in the U3Si2 fuel, and the radiation-induced defects using first-principles calculations. We are going to calculate the solubility of fission products Mo, Zr, Ce, Ru, Pr, Y, Gd, Ba in the U3Si2 fuel, as well as the transuranic Pu, by calculating the energies for forming various defects in a U3Si2 supercell. Additionally, from the induced volume variation of the U3Si2 supercell, we can determine the effect of the fission product or Pu on the swelling of U3Si2. The calculated total energies of supercells with defects will be further used for analyzing the mixing energies, which will give information on whether a more stable secondary fission product or Pu phase can precipitate in U3Si2 fuel matrix. Lastly, to gain insight into the radiation damage and recovery from radiation damage in U3Si2, we are going to calculate the energies for forming Frenkel pairs and Schottky defects. For this study, we are going to use the DFT+U method, with a U-value of 1.5 eV for the uranium and plutonium atoms, and 2x2x3 supercell of the U3Si2 primitive cell. We are going to consider three substitutional defects (U1, U2, and Si), four interstitial sites, and Frenkel pairs and Schottky defects at three different distances. Because for calculating the defect formation and mixing energies the total energies of the fission products and Pu phases are required, we are also going to relax their binary and ternary phases. |
| Award Announced Date | 2019-05-14T16:05:37.433 |
| Awarded Institution | Center for Advanced Energy Studies |
| Facility | Microscopy and Characterization Suite |
| Facility Tech Lead | Alina Zackrone, Yaqiao Wu |
| Irradiation Facility | None |
| PI | Vancho Kocevski |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1767 |