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[en] Most building materials of terrestrial origin contain small amounts of Naturally Occurring Radioactive Materials (NORM), mainly radionuclides from the 238U and 232Th decay chains and the radioactive isotope of potassium, 40K. The external radiation exposure is caused by gamma emitting radionuclides, which in the uranium series mainly belong to the decay chain segment starting with 226Ra. The internal (by inhalation) radiation exposure is due to 222Rn, and its short lived decay products, exhaled from building materials into the room air. Due to economical and environmental reasons there is an increased tendency to use recycled industrial by-products containing Technologically Enhanced Natural Occurring Radioactive Materials (TENORM) in the building material industry. Fly ash (FA), produced as by-product in the combustion of coal, is extensively used in Israel since the early nineties of the last century in concrete and as an additive to cement (1). The increase of 226Ra activity concentration, the mineralogical characteristics of the FA and of the concrete may influence on the radon exhalation rate and consequently on the radon exposure of the public. The recently published Israeli Standard 5098 (IS 5098) 'Content of natural radioactive elements in building products' (2) limits the content of natural radionuclides as well as the radon emanation from concrete. This paper present a study conducted to investigate and quantify that influence and to correlate between in-situ and laboratory measurements
[en] The Israel isolated electrical system emphasizes the need for energy security of supply by diversification of energy sources for electricity production.Nuclear Power is considered as one of the most efficient technologies for achieving these goals as well as for climate change mitigation efforts. We will present below the benefits and the risks for introducing a Nuclear Power Plant (NPP) in Israel electricity generation system, considering recent repercussions of the Fukushima accident. Simulations of introduction a NPP in Israel Electric system showed an increase of reliability and a reduction of electricity generation cost in case of long gas shortcuts. In addition, NPP introduction will reduce significantly greenhouse gas emissions without considerable increase of electricity generation cost.Some NPP safety aspects will also be evoked and the additional risk to the population and the environment will be evaluated, following sitting of a Generation III+ NPP (Westinghouse's AP1000 and Areva's EPR technologies) at the Shivta site in the Negev desert area
[en] In this paper we discuss Canada's response to the March 2011 events at Fukushima, from a nuclear regulatory point of view, including emergency management. We will also describe the actions taken by the Government of Canada and the challenges with obtaining timely and complete information. Finally, three specific actions taken by the CNSC, namely the establishment of a Fukushima Task Force, the creation of an External Advisory Committee and the results of an IA EA review of the Canadian Nuclear Safety Commission (CNSC) response to the events at Fukushima are summarized.
[en] Knowledge of the beam energy and phase distributions at SA RA F1 are essential for both user experiments and beam dynamics design. While the target experiments need to know the energy distribution after the accelerating module, to design the beam dynamics needed to reach this energy, it is necessary to know the 2D energy and phase distributions at the entrance to the accelerating module. The beam energy distribution is measured after the accelerating module by Rutherford Scattering (R S) of the part of the beam into a silicon detector. This report describes the method used to measure the resolution of this measurement as well as the method used to measure the 2D energy and phase distributions at the entrance to the SARAF accelerating module.
[en] A previously unknown neptunium-transition-metal binary compound, Np2Co17, has been synthesized and characterized by means of powder x-ray diffraction, 237NpMossbauer spectroscopy, SQUID magnetometry, and x-ray Magnetic Circular Dichroism (XMCD). The compound crystallizes in the Th2Ni17-type hexagonal structure, with room temperature lattice parameters a = 8.3107(1) A and c = 8.1058(1) A. Magnetization curves indicate the occurrence of ferromagnetic order below a TC > 350 K. Mossbauer spectra suggest a Np3+ oxidation state and give an ordered moment of fÊNp = 1.57(4) B and fÊNp = 1.63(4) fÊB for the Np atoms located, respectively, at the 2b and 2d crystallographic positions of the P63/mmc space group. Combining these values with a sum rule analysis of the XMCD spectra measured at the neptunium M4,5 absorption edges, one obtains the spin and orbital contributions to the site-averaged Np moment (fÊS = -1.88(9) fÊB, fÊL = 3.48(9) fÊB). The ratio between the expectation value of the magnetic dipole operator and the spin magnetic moment (fÊmd/fÊS = +1.36) is positive as predicted for localized 5f electrons, and lies between the values calculated in intermediate coupling (IC) and in jj approximations. The expectation value of the angular part of the spin-orbit interaction operator is in excellent agreement with the IC estimate. The ordered moment averaged over the four inequivalent Co sites, as obtained from the saturation value of the magnetization, is fÊCo∼1.6 fÊB. The experimental results are discussed against the predictions of first-principle electronic structure calculations based on the spin-polarized local spin density approximation plus Hubbard interaction.
[en] The interest in the possible health hazards of occupational exposure of MRI workers to electromagnetic fields, and the compliance with the relevant safety standards has recently increased. One of the reasons for this is the Physical Agents (Electromagnetic Fields) Directive adopted by the European Union in 2004(1), which was due to be incorporated into the domestic legislation of member states by April 2008. Restrictions imposed by this directive would adversely affect current clinical MRI activities. In view of the concern raised by the MRI community, the deadline for the implementation of the directive was postponed to April 2012, so as to allow sufficient time to take into account new recommendations from relevant international bodies. Here we present the results of comprehensive measurements of the static magnetic fields in the vicinity of the MRI systems in medical centers in Israel
[en] 90Sr - 90Y is one of the main sources of internal exposure, and the common method used to estimate its uptake is by measuring urine samples. Based on international safety standards (1) the derived reference level for 90Sr-90Y is 2.2 Bq/L. Since the MDA (Minimum Detectable Activity) for direct urine measurement is higher than this level, special treatment of the urine sample must be employed. It mostly includes steps of concentration, chemical treatment, and preparation for counting. The disadvantages of the common methods are elaborate work, use of expensive materials and possible limited accuracy due to usually direct beta counting. The possible contribution of 60Co, fission products as 137Cs, or the natural 40K in urine, may also be significant. Beta particles with energy in excess of 263 keV produce Cherenkov photons in aqueous solutions, which can be detected and quantified. Cherenkov radiation measurements can be performed by using the light detection features implemented in liquid scintillation counting systems. When measuring 90Sr-90Y activity in urine by Chrenkov counting, most of the Cherenkov radiation is produced by 90Y (about 98.6%, Emax=2280kev) due to the lower energy of the beta particles from 90Sr (Emax = 546 KeV). There is no chemical quenching when employing Cherenkov counting, however, the counting efficiency varies strongly with color quenching, at a greater extent than in standard liquid scintillation counting (2), and therefore proper quench correction techniques must be employed. In a previous publication (3) it was shown that a quench correction method based on the external source of some Liquid Scintillation systems can be applied. The method (named ESAR- External Source Area Ratio) uses an indicative parameter based on the integral area of the spectra, and it was shown that it is superior to the common methods which use conventional indexes (4). In the present work, the application of the ESAR method for determination of 90Sr-90Y in human urine samples is described
[en] During the last decade the Democratic People’s Republic of Korea (DPRK) conducted a total of four declared underground nuclear tests in 2006, 2009, 2013 and 2016. The tests were detected by the International Monitoring System (IMS) (seismic, infrasound and radionuclide stations) which is a part of the verification regime of the Comprehensive Test Ban Treaty Organization (CTBTO). Based on the analysis of the seismic waveforms from the IMS, the tests were found to be in the vicinity of the Punggye-ri area and the signals had the characteristics of shallow events.The international seismic stations that detected the nuclear test in 2016 are shown on the world map in Figure 1b The 27 primary seismic stations that made the initial detection of the nuclear test in 2016 ; The red dot indicates the signal source - Punggye-ri test site In contrast to the seismic ''signature'', the radionuclide technology is the only monitoring technology employed by the CTBTO that can provide clear evidence of the nuclear nature of an explosion (''smoking gun''). After an underground nuclear explosion radioactive fission products can seep through layers of rock and sediment until they escape into the atmosphere. The fission products (mostly noble gases) are dispersed in the atmosphere and may be detected thousands of kilometers downwind. Indeed, more than 7 weeks after the test in 2013, unusual detections of xenon isotopes were reported at the radionuclide station in Takasaki, Japan located at around 1000 km from the DPRK test site The purpose of this study is to summarize the main findings about the four nuclear tests in the DPRK based on the nuclear monitoring technologies
[en] At the beginning of the nuclear era research and development on research reactor (RR) fuel was essentially driven by the need to optimize design and operation of different purpose-oriented facilities. Over the years, due to increasing security and non-proliferation concerns, the motivation for research and development on RR fuel changed drastically. The focus of research moved to development of higher density fuels to allow operation of existing and future facilities without the use of Highly Enriched Uranium (HEU). From that time on the paradigm orientating RR fuel development has been to reduce fuel enrichment to below 20% 235U while minimizing the impact on performance and economic metrics of the RR
[en] The main goal of this work is to evaluate the THERMO-T code capabilities as a transient thermal-hydraulic-neutronic solver for MTR plate-type cores. The calculation scheme utilizes the Serpent code for prediction of the 3D power distribution and shape in core calculations. The obtained 3D power distribution is then passed to THERMO-T for calculation of various parameters prediction. The amplitude of the power profile is changed by a coupled point-kinetics (PK) model. The benchmark problem is specified in the IAEA-TECDOC-643.This article reports on the first stage in the development of a transient thermal-hydraulic system code for research reactor accidents analysis - THERMO-T, which eventually will interface with DYN3D, a 3D multi-group nodal diffusion neutron flux solver, to form a 3D TH-NK transient package for research reactors. In this paper an examination of the LOFA transient analysis is presented