Analysis on Enrichment and Mass of Uranium Materials With Time-Correlated Measurement
Abstract Effective determination for enrichment of the uranium materials in heavy shielding is technically difficult to solve. Various technical methods so far have been proposed to deal with this problem. With the time-correlated coincidence measurement method, 14 MeV neutrons and fission spectrum neutrons are chosen to interrogate the uranium samples with different masses and enrichments. The fission spectrum neutrons are obtained by slowing down the 14 MeV neutrons. Results have shown that a good linear relationship exists between masses of the uranium materials (⩽10% enriched 235U) that possess the same enrichment. A linear relationship also exists between enrichments of the uranium materials that possess the same mass.
Time-correlated pulse-height measurements of low-multiplying nuclear materials
Abstract Methods for the determination of the subcritical neutron multiplication of nuclear materials are of interest in the field of nuclear nonproliferation and safeguards. A series of measurements were performed at the Joint Research Center facility in Ispra, Italy to investigate the possibility of using a time-correlated pulse-height (TCPH) analysis to estimate the sub-critical multiplication of nuclear material. The objective of the measurements was to evaluate the effectiveness of this technique, and to benchmark the simulation capabilities of MCNPX-PoliMi/MPPost. In this campaign, two low-multiplication samples were measured: a 1-kg mixed oxide (MOX) powder sample and several low-mass plutonium–gallium (PuGa) disks. The measured results demonstrated that the sensitivity of the TCPH technique could not clearly distinguish samples with very-low levels of multiplication. However, the simulated TCPH distributions agree well with the measured data, within 12% for all cases, validating the simulation capabilities of MCNPX-PoliMi/MPPost. To investigate the potential of the TCPH method for identifying high-multiplication samples, the validated MCNPX-PoliMi/MPPost codes were used to simulate sources of higher multiplications. Lastly, a characterization metric, the cumulative region integral (CRI), was introduced to estimate the level of multiplication in a source. However, this response was shown to be insensitive over the range of multiplications of interest.
Population and Settlement
Part 1 Population distribution: world population distribution variations in world population distribution population distribution in the Highlands and Islands population distribution in Japan population distribution in Brazil. Part 2 Population growth and movement: population structure the world population explosion variations in population growth migration why do people migrate types of migration in North and West Africa West German migration populating the USSR populating Australia attitudes to population control population and natural resources. Part 3 Settlements: location of settlement settlement types settlement functions settlement patterns South Wales valley settlements the changing village. Part 4 Urbanization: million cities world urbanization rural-urban migration in the developing world urban land use inner city problems urban transport the Tyneside metro spheres of influence changing shopping habits the Dutch Randstad Lagos - a city in the developing world new and expanding towns in the UK new settlements in developing countries green belts or red bricks? Part 5 Further studies: UK population migration Kenya's population problems Sheffield Washington New Town.