Nuclear Science and Techniques

Calculation of the neutron noise induced by fuel assembly vibrations in two pressurized water reactor (PWR) cores has been conducted to investigate the effect of cycle burnup on the properties of the ex-core detector noise. An extension of the method and the computational models of a previous work have been applied to two different PWR cores to examine a hypothesis that fuel assembly vibrations cause the corresponding peak in the auto power spectral density (APSD) increase during the cycle. Stochastic vibrations along a random two-dimensional trajectory of individual fuel assemblies were assumed to occur at different locations in the cores. Two models regarding the displacement amplitude of the vibrating assembly have been considered to determine the noise source. Then, the APSD of the ex-core detector noise was evaluated at three burnup steps. The results show that there is no monotonic tendency of the change in the APSD of ex-core detector; however, the increase in APSD occurs predominantly for peripheral assemblies. When assuming simultaneous vibrations of a number of fuel assemblies uniformly distributed over the core, the effect of the peripheral assemblies dominates the ex-core neutron noise. This behaviour was found similar in both cores.

To carry out accurate burnup calculations for a pebble-bed fluoride-salt-cooled high-temperature reactor, the energy-dependent cross-sectional model based on the Doppler broadening rejection correction method has been proposed to develop the energy-dependent elastic scattering cross-sectional model. In this study, the Monte Carlo continuous energy code PSG2/Serpent was used to examine the difference between the constant cross-sectional model and the energy-dependent cross-sectional model during burnup. For the cases analyzed in this study, numerical simulations show that the multiplication coefficient was improved by hundreds pcm and 239Pu concentration was improved by approximately 1–2% during burnup when the energy-dependent elastic scattering cross-sectional model is considered.

Lambda polarization can be measured through its self-analyzing weak decay, making it an ideal candidate for studying spin effects in high-energy scattering. In lepton-nucleon deep inelastic scattering (DIS), Lambda polarization measurements can probe polarized parton distribution functions (PDFs) and polarized fragmentation functions (FFs). One of the most promising facilities for high-energy nuclear physics research is the proposed Electron-ion collider in China (EicC). As a next-generation facility, EicC is set to advance our understanding of nuclear physics to new heights. In this article, we study the Lambda production in electron-proton collisions at the EicC energy, in particular the reconstruction of Lambda based on the performance of the designed EicC detector. In addition, taking spontaneous transverse polarization as an example, we provide a theoretical prediction with a statistical projection based on one month of EicC data, offering valuable insights into future research prospects.

The quantification of ionizing energy deposition and non-ionizing energy deposition plays a critical role in precision neutron dosimetry and in the separation of the displacement damage effects and ionizing effects induced by neutron radiation on semiconductor devices. In this report, neutrons generated by the newly built China Spallation Neutron Source (CSNS) are simulated by Geant4 in semiconductor material silicon to calculate the ionizing and non-ionizing kerma factors. Furthermore, the integral method is applied to calculate neutron-induced ionizing at the CSNS and non-ionizing kerma factors according to the standard neutron nuclear database and the incident neutron spectrum. In addition, thermoluminescence dosimeters are utilized to measure the ionizing energy deposition and six series of bipolar junction transistors are used to measure the non-ionizing energy deposition based on their neutron damage constants. The calibrated kerma factors that were experimentally measured agreed well with the simulation and integral calculation results. This report describes a complete set of methods and fundamental data for the analysis of neutron-induced radiation effects at the CSNS on silicon-based semiconductor devices.

Open plasma stealth technology excited by radionuclides is known to have several problems: (1) owing to disturbance from airflow, the plasma distribution is unstable. (2) The plasma is highly dependent on the atmosphere; therefore, it is difficult to modulate in target stealth. (3) Concerns regarding radiation harassment prevent the application of this method. To avoid these problems, an enclosed plasma stealth method is introduced. Via simulation on an infinite conducting plate, this method was found to effectively solve the above concerns, which may offer a new approach for the practical application of plasma stealth technology excited by radionuclides, especially for small-satellite stealth because of its lightweight and self-provided plasma.