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Low Activation-Modified High Manganese-Nitrogen Austenitic Stainless Steel for Fast Reactor Pressure Vessel Cladding :: Science Publishing Group

Low and free nickel austenitic stainless steel alloys were developed successfully and proposed to be used as a liquid sodium coolant fast reactor pressure vessel cladding. A standard austenitic stainless steel SS316L (AISI 316L) was produced as a reference sample. The nickel content was partially or totally replaced by manganese and nitrogen. The microstructure of the produced stainless steel alloys was investigated using Schaeffler diagram, optical microscopy and X-ray diffraction patterns (XRD). Mechanical properties of the developed stainless steel grads were investigated using Vickers hardness, impact and tensile tests at room temperature. Sodium chloride was used to study the corrosion rate of the investigated alloys by open circuit potential technique. Slow and total slow neutrons removal cross sections were measured using 241Am-Be neutron source and highly calibrated He-3 detector. Eight gamma ray lines which emitted from 60Co and 232Th radioactive sources and HPGe detector were used to study the attenuation parameters of the produced alloys. Metallography, Schaeffler diagram and XRD results showed that all the produced stainless steels are mainly of austenite phase with a small ferrite phase. The developed manganese-nitrogen stainless steels showed higher hardness, yield and ultimate tensile strength than SS316L. The elongation of developed stainless steels is relatively lower than the standard SS316L. The impact toughness was reduced with replacement of Ni by Mn. The developed manganese stainless steels have a higher total slow removal cross section than SS316L. On the other hand, the slow neutron and gamma rays have nearly the same behavior for all studied stainless steels.

Design of Vacuum Compatible Automatic Targets Feeding System :: Science Publishing Group

The present paper presents the design of a vacuum compatible automatic targets feeding system (VCATFS) that can be used to introduce targets inside the interaction chambers for accelerators, laser beams and others research plants. As a first application, the system is to be used within the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) project, to load target frames in the interaction chamber without losing the vacuum. The target frames will be inserted and retracted into/from the interaction chamber individually with high accuracy of positioning. Up to three target frames can be used during one experiment. This number of targets is a consequence of several severe spatial constraints where the system will be installed, but for other situations it can be increased. Also, a new technique of moving the target frames is proposed, two horizontal translations in two parallel planes and two vertical translations also in two parallel planes. VCATFS is divided into two main sub-systems: mechanical (includes kinematics, high precision components and systems, vacuum chamber), and a dedicated command and control system (transducers - high accuracy absolute linear encoders, stepper motors and ociated electric drives unit, interfaces and proprietary software). Additionally, a dedicated vacuum system was designed. This approach will further be developed as prototype level. This paper will focus on the design of mechanical sub-system, the remaining ones will be the subject of future do ents that would be made publicly available in the future.

Revealing

226Ra alpha peak was revealed by a Multi-Pixel Photon Counter (MPPC) through a developed spectrometer. MPPC is consisted of silicon photomultipliers (Si-PM) which can be used for photon detection and measurement. It is one of the new generation counter types. It has been used in many research areas such as radiation detection and optics. So, this type detector was chosen so that this study is up-to-date. Main goal of the study is to obtain pure alpha energy spectrum because no study was found in the literature about the neat alpha spectrum by the MPPC. For this reason, coincidence gate method was used in the presented study to acquire the spectrum. In the first section, alpha spectrum was recorded directly via MPPC module. This spectrum had too much electronic noise. The spectrum was secondly obtained through the developed spectrometer. This second spectrum had not almost all noise components. Then, the obtained spectra were compared with each other at the final section. The erted spectrometer was highly successful in obtaining neat alpha spectrum by reducing the most noise components. It has been realized that the neat source spectra of other radioactive sources can be achieved by using this spectrometer with MPPC. Additionally, students who work about radiation detection can use the suggested spectrometer in their experiments.

Natural Radionuclides Concentrations and Annual Effective Dose in Seasonal Fruits of ladesh :: Science Publishing Group

The aim of the present study was to investigate the activity concentrations of natural radionuclides in different seasonal fruits of ladesh. In total 20 samples of 16 different kinds of fruits were collected from the local markets of ladesh. The radioactivity of these samples was measured by using Gamma Spectrometry System. The radioactivity of natural radionuclides in the studied seasonal fruit samples were found to be ranged from BDL to 31.13±10.63 Bqkg-1 with an average 10.95 Bqkg-1 due to 238U, from 1.55±0.73 to 34.59±7.43 Bqkg-1 with an average 6.68 Bqkg-1 due to 232Th and from BDL to 733.25±61.17 Bqkg-1 with an average 308 Bqkg-1 due to 40K. Artificial radionuclide was not found in the studied fruit samples. The maximum activities of 238U, 232Th and 40K were observed, respectively in coconut, jujube and papaya. However, the average concentrations of all radionuclides mentioned above in the studied samples were found to be less than the world average. The total annual internal effective dose from the consumption of radioactive fruits was found to be 8.39 μSv/y. The value the annual effective dose in all samples in this study was lower than ICRP 72; therefore, the values natural radioactivity and annual effective dose in the seasonal fruits are found to be safe and no health-hazards are createdfor the population of ladesh.

essment of Natural Radioactivity Levels and Radiological Hazards of Cement in Iraq :: Science Publishing Group

Eight samples of cement were collected from different commercial factories (Al-Koufa, Al-Basra, Al-Najaf and Kerkouk factories) located in Iraq. They were yzed using a gamma ray spectroscopy system. The activity concentrations of 226Ra, 232Th and 40K were ranged from 5.8 to 43.17 Bq kg-1, from 0.99 to 55.79 Bq kg-1 and from 53.28 to 185.34 Bq kg-1, respectively. The potential radiological hazards were essed by calculating the radium equivalent activity (Raeq), the indoor absorbed gamma dose rate (D), the annual effective dose equivalent (AEDE), the alpha index (Iα), the gamma index (Iγ), and the external hazard (Hex) and internal hazard (Hin) indices. The highest value of Raeq is estimated of 101.36 Bq kg-1, which is significantly less than the upper limit of 370 Bq kg-1. The estimated maximum value of the absorbed gamma dose rate of 54.71 nGy h-1 is within the world average value of 55 nGy h-1, and the annual effective dose equivalent in the studied samples were 0.05 (outdoor), 0.18 (indoor) mSv y-1, which is lower than the recommended limit reported in the UNSCEAR (2000). The values of the hazard indices were below the recommended levels; therefore, the study shows that the measured radioactivity for cement does not pose as significant source of radiation hazard and is safe for use in the construction of dwellings.