Figure 3 - uploaded by Shengli Chen
Content may be subject to copyright.
Source publication
Atomic displacement is one of the key factors that influence the behaviors of material properties during and after irradiation. Many models, including the international standard metric Norgett-Robinson-Torrens model (NRT), have been developed to calculate the number of Displacement per Atom (DPA) using the energy of Primary Knocked-on Atom (PKA) as...
Contexts in source publication
Context 1
... DPA cross sections of 56 Fe calculated with the lastest released JEFF-3.3 library [20] is presented in Figure 3 for the NRT, ARC, and CB formulae, respectively. Small difference between the ARC-DPA and CB-DPA cross sections is observed. ...
Similar publications
Irradiation damage is an important cause of material failure in in-service nuclear reactors. It is important to explore the resistance to irradiation of metals with different crystal structures. As the formation and evolution of point defects on the atomic scale caused by cascade collisions in the early stages of irradiation are currently difficult...
Citations
... For Al metal, the classical NRT model is more consistent with measures than the other three models. The three measures above 1 MeV for Al are higher than theoretical calculations due to the possible underestimation of the NRT model near 2.5E d , as the examples shown in Ref. [57]. ...
Radiation damage is a common challenge for materials employed in a radiation environment. The present work performs experimental validation of current primary radiation damage models for recoil energy near the displacement threshold using electron irradiation experimental measures. The verified rescaling of resistivity change per Frenkel pair results in reasonable agreements between theories and experiments. The recent molecular dynamics-based model is demonstrated as consistent with experimental data for Fe, Ni, and Cu, whereas the classical step function approximation of the displacement probability is shown more adequate for Al and Ti. Further investigation is needed for Ag due to the excellent agreement with the not yet well supported rescaled experimental data. The validated primary radiation damage model of Fe leads to a ∼1/3 increase in gamma photon-induced displacement damage in nuclear reactor applications.
Because the irradiation damage is a major challenge of nuclear materials, it is of upmost importance to accurately calculate it with reliable uncertainty estimates. The main objective of this thesis is to develop and improve the methodologies for computing the neutron irradiation-induced displacement damages as well as their uncertainties. After a brief review on nuclear reaction models and primary radiation damage models, we propose a complete methodology for calculating damage cross sections from different nuclear reactions and the subsequent calculation of Displacement per Atom (DPA) rates.The recoil energies from neutron-induced reactions are summarized with an estimation of the relativistic effect and the target thermal vibration. Particularly, a new method for computing the recoil energy from charged particle emission reactions is proposed by considering both the quantum tunneling and the Coulomb barrier. Some methods are developed to improve and verify numerical calculations. Damage cross section calculations from neutron radiative capture reaction and N-body reactions are also thoroughly analyzed and discussed. In addition to the neutron irradiation-induced displacement damage, the electron, positron, photon-induced DPA cross sections, as well as the beta decay and Fission Products (FPs)-induced damage are also investigated. Orders of magnitude of their relative contributions are given.For the neutron irradiation-induced DPA rate calculation, attention should be paid when using infinite dilution cross sections. E.g., in the ASTRID inner core, the self-shielding correction on ECCO 33-group damage cross sections leads to a 10% reduction of DPA rate, whereas the multigroup correction is still not automatically treated for DPA rate calculation in neutronic codes nor for computing Primary Knock-on Atom (PKA) spectrum. Based on the presently proposed method for computing the FPs-induced DPA by atomistic simulations, the peak value of the FPs-induced DPA rate can be 4 to 5 times larger than the neutron-induced one in the cladding of the ASTRID inner core, even though the penetration of FPs in the Fe-14Cr cladding is less than 10 µm. Therefore, the question of whether the FPs-induced damage should be considered for determining fuel assembly lifetime in fast reactors needs to be discussed.In the reactor vessel of a simplified pressurized water reactor, the covariance matrices of 235U prompt fission neutron spectrum from ENDF/B-VII.1 and JENDL-4.0 respectively lead to 11% and 7% relative uncertainty of DPA rate. Neglecting the correlations of the neutron flux and PKA spectrum results in an underestimation by a factor of 21. The total uncertainties of damage energy rate are respectively 12% and 9%, whereas an underestimation by a factor of 3 is found if the correlations of damage cross section and neutron flux are not considered.
