نشریه تابش و فناوری هسته ای
سال چهارم شماره 1 (بهار 1396)

In this investigation, it is tried to measure the spectrum of emitted gamma from 22Na source with energy of 511 that is created by annihilation of electron and positron in different angle by two NaI detectors with resolving time 4 . This measurement is done in states with using lead shielding and without using of them for detectors. Procedure of experiment is follow as: the two detectors are placed vertically on side of the positron source without using of lead shielding. Spectrum of the entrane gamma to detectors were recorded in the coincidence state. Then detectors was designed to laed shielding. Two detectors were placed in front of the source and again Spectrum of the entrane gamma to detectors were recorded in the coincidence state. The measured area below of 511 gamma peak in gamma spectrum for different angles shows more narrow width for the case that lead shielding used than the case that lead shielding did not used and this is because of reducing campton effect by using lead shielding.

Shock ignition (SI) is one of the attractive topics for inertial confinement fusion (ICF). This two-step ICF process separates fuel assembly and ignition, relaxing the driver requirements and promising high gains. One of the main concerns about current working on nuclear power Reactor is the potential hazards of their radioactive waste. In the design of future fusion power plants, there still exist radiological hazards due to accumulation of byproduct tritium in blanket layer and also collisions between 14.1MeV neutrons released from Deuterium- Tritium(DT) fusion reaction and nearly all fusion reactor building materials. Therefore, in this paper, ignition requirements and fuel gain of non-equimolar DT fuel pellet have been studied in SI scheme. Our calculations show that the hot-spots formation conditions depend on densities of hot-spot and its surrounding cold fuel. Finally, the role of physical parameters on energy gain is investigated, including fuel mass, the ratio of hot- spot pressure to cold fuel pressure, different tritium weight fractions and isentrope parameter.

Abstract: Since the neutronic calculation of a nuclear reactor is a basis for designing other parameters such as thermal hydraulic, safety, etc., thus, in this work the neutronic and kinetic parameters of the next generation SMR reactor called NuScale have been calculated and analyzed. These parameters include the effective multiplication factor (keff), neutron flux, axial and radial power peaking factor, effective delayed neutron fraction and prompt neutron lifetime. Moreover, the burn up calculation is performed to find the mass changes in fissile isotopes such as 235U and 239Pu, burnable poison material and some of important fission fragments. The acid boric concentration in the coolant has been found about 1.8 g/kg in the criticality condition. Also, the average values of thermal, epithermal and fast neutron fluxes are obtained about 1.85×1013, 8.79×1013 and 3.67×1013□(n/(〖cm〗^2.s)), respectively. In addition, the values of neutronic and kinetic parameters are decreased in the present of acid boric. The results show that in the beginning of cycle (BOC) the keff value is decreased suddenly due to Xe production and then the neutron absorption by Gd burnable poison. Afterwards, this parameter is increased due to the production of fission fragments and the spatial self-shielding property of Gd fuel rods. Finally, we can see that Gd burnable poison causes increasing of the value of keff parameter in during the cycle.

Scientists, based on the evidence, believe that nearly 4 percent of the universe is visible and the remaining 96 percent consists of dark matter and dark energy. Hereby, the development of the accelerator technology and high energy physics were considered extensively.
ILC is the most powerful of proposed accelerator that is planned to have collision energy of 500GeV initially, with the possibility for a later upgrade to 1000GeV (1 TeV). The most powerful of proposed accelerator that is an alternative for the LHC accelerator is ILC. After being accelerated to the desired energy in a linear accelerator, beam could be transport from the exit of the main linacs to the interaction point. Since we need maximum possibility in the interaction point, beam lines are equipped with electromagnetic multipoles for beam transport and focusing, in such systems. Due to energy loss by beam passing through the electromagnetic multipoles, beam line designing is important to conserve beam energy in beam transport. In this paper, simulation of BDS was done by use of the BDSIM-Geant4 code. Then, beam characteristics were evaluated by use of the some criteria such as emittance. We estimated the distribution of particles at the beginning and end of the BDS line, to find minimum beam size at the interaction point. Finally the amount of energy loss within 100 meters of the lines was studied.

Safe operation and maximum burning of fuel material are two issues that are recently considered in nuclear fuel rod fabrication industry. Any failure in nuclear fuel and cladding, such as fuel rod ballooning or pellet-clad high contact pressure, may cause release of radioactive fission fragments to the reactor coolant, which is an undesirable issue from the reactor safety point of view. To have a correct prediction of fuel rod performance used simulator codes, In this paper the simulation of mechanical part of Bushehr VVER-1000 fuel rods operation done with the rigid pellet and thin cylindrical model.
Empirical relationships and numerical algorithms to solve equations somehow have been selected to mechanical parameters such as the fuel rod’s outer radius and stress-strain of clad are carefully prediction. Mechanical performance Simulations Results of VVER-1000 fuel rod in good agreement with FRAPCON-3.3 output. The models used in this paper can be used to evaluate the performance of future native reactor fuel rods.

The Purpose of this study was to calculate kinetic parameters Tehran Research Reactor sensitivity analysis taking into account the effect of temperatures feedback using the code MCNPX. Kinetic parameters including effective delayed neutron fraction (βeff) and the mean generatin time (Λ). The exact calculation of these parameters is very important for immune function and Reactors control. And to play an important role in the analysis of the system dynamic. In this study by changing the temperature, and other materials used in the core of Tehran Research Reactor from 20 O C to 100 O C The effects of temperature change on the reactor kinetic parameters for both 70C and 60C library which are at 20 O C or 293 O K and for fuel enrichment 20% and 80% have been investigated. Results show that The effective multiplication factor (Keff) by changing temperature is reduced for both cross section and for both enrichment. And its value by increasing temperature in 70C library is more than 60C library in both Enrichment. The prompt life time (ℓ) and effective delayed nutron fraction(βeff) values rising temperature increases in both library and both enrichment. And the amount of them by increasing temperature in 70C library are more than 60C library in both enrichment. The amount of mean generation time (Λ) considering changes in temperature rise in 60C library is more than 70C library But generally such as prompt life time (ℓ) parameter by incrasing temprature shows an increasing trend in both 20% and 80% enrichment.