Theoretical Calculations of the Cross-sections for (n,α) and (n,xα) reactions on the Structural Material for Fusion Reactor 46-50Ti

The biggest problem of structural materials for fusion reactor is the damage caused by the fusion product neutrons to the structural material. If this problem is overcomed, an important milestone will be left behind in fusion energy. One of the important problems of the structural material is that nuclei forming the structural material interacting with fusion neutrons are transmuted to stable or radioactive nuclei via (n, x) (x; alpha, proton, gamma etc.) reactions. In particular, the concentration of helium gas in the structural material increases through deuteron- tritium (D-T) and (n, α) reactions, and this increase significantly changes the microstructure and the properties of the structural materials. Therefore, in this study, the effects of the different nuclear level density models on the excitation functions of the (n, α) reactions on 46-50Ti isotopes, an attractive candidate for the structural material for fusion reactors, have been investigated for the first time. Also, the differential cross-sections with respect to alpha energy for the emission of alpha particles of the 46-50Ti (n, xα) reactions have been investigated at 14.1 MeV incident neutron energy. The calculations are performed using the two-component exciton model in the TALYS 1.9 code, and the results are compared with available experimental data. The results of this study will contribute to nuclear database as required for improving, design and operations of the important facilities as ITER (International Thermonuclear Experimental Reactor), DEMO (The demonstration power plant) and ENS (European Nuclear Society).

T-dependent RMF Model Applied to Ternary Fission Studies

Ternary decay is comparatively a rare phenomenon. The yield distribution for the thermal neutroninduced fission of 236U was investigated within the Temperature-dependent Relativistic Mean Field (TRMF) approach and statistical theory. Binding energy obtained from TRMF for the ground state and at a specific temperature is used to evaluate the fragment excitation energy, which is needed to calculate the nuclear level density. Using the ternary convolution, the yield for α-accompanied fission of 236U* is calculated. Initial results are presented which shows a maximum yield for the fragment pair Tc + Ag +α. Further, the ternary pre-existence probability for the spontaneous fission of 236U was studied considering fixed third fragments of α,10Be and 14C using the area of the overlapping region. No significant change in the yield distribution was observed when fragment deformations are considered. However, the heavy group for the probable pair remains as 132Sn with a change in mass number of the lighter fragment.

Updated nuclear level density parameters of 153Sm nucleus within the back-shifted Fermi gas model

The present work re-evaluates the level density parameter a, asymptotic level density parameter aasy, and back-shifted energy parameter E1 within the back-shifted Fermi gas model (BSFG) for the 153Sm nucleus. This reevaluation is based on the experimental nuclear level scheme extracted from the ENSDF library, the average level spacing at the neutron binding energy (D0 value), and the latest updated nuclear level scheme obtained from an experimental gamma cascade experiment, which was performed at the Dalat Nuclear Research Reactor using the thermal neutron beam. The updated values of the BSFG level parameters are: (1) a=18.09±0.25 MeV-1and E1=-0.92±0.07 MeV for the energy-independent level density parameter; and (2) aasy=15.00±0.20 MeV-1and E1=-0.81±0.08 MeV for the energy-dependent level density parameter. It has been found that the total nuclear level densities calculated using these updated parameters agree with the experimental data better than those using parameters taken from the nuclear reference database RIPL-3. These updated parameters are more accurate and reliable than those extracted from RIPL-3 and are, therefore, highly recommended for all the applications hereafter.