Kros C.,NECSA |
Weiner R.,Sandia National Laboratories
Packaging, Transport, Storage and Security of Radioactive Material | Year: 2013
The transportation safety case for transporting spent nuclear fuel is a requirement for licensing. It has both qualitative and semiquantitative aspects. The qualitative aspects include transportation regulations, radiation dose limits, role of the transportation package in transportation, transportation package certification process, training, emergency response, the performance of the transportation package in accidents and the evaluation of past transportation accidents. The quantitative aspects support the qualitative descriptions. Radiation doses accrued by members of the public and by workers are calculated using the code RADTRAN. Dose from both routine, incident free highway transportation and from highway transportation accidents are part of the safety case and will be compared with both background doses and the regulatory safety criteria. The radiation doses from routine transportation are calculated for the following: the maximally exposed member of the public, doses to vehicle escorts and doses to vehicle crew. Collective doses to populations are calculated for representative routes. Collective dose depends on the number of people affected as well as on the extent of the radiation from the source to which reference groups are exposed. Accidents involving loss of gamma shielding and loss of confinement integrity are discussed, as are accidents in which there is no impact on the cargo. © 2014 W. S. Maney & Son Ltd.
AIP Conference Proceedings | Year: 2011
A key feature of neutron based interrogation systems is the need for adequate provision of shielding around the facility. Accelerator facilities adapted for fast neutron generation are not necessarily suitably equipped to ensure complete containment of the vast quantity of neutrons generated, typically >1011ns-1. Simulating the neutron leakage from a facility is not a simple exercise since the energy and directional distribution can only be approximated. Although adequate horizontal, planar shielding provision is made for a neutron generator facility, it is sometimes the case that vertical shielding is minimized, due to structural and economic constraints. It is further justified by assuming the atmosphere above a facility functions as an adequate radiation shield. It has become apparent that multiple neutron scattering within the atmosphere can result in a measurable dose of neutrons reaching ground level some distance from a facility, an effect commonly known as skyshine. This paper describes a neutron detection system developed to monitor neutrons detected several hundred metres from a neutron source due to the effect of skyshine. © 2011 American Institute of Physics.
AIP Conference Proceedings | Year: 2011
Since natural coloured sapphire (α-Al2O3) commands a high gem stone market price there is a need for a reliable method of identifying artificially coloured sapphire that has an inherently lower value. Diffusing beryllium into sapphire at high temperatures results in a coloured stone virtually indistinguishable from a natural one. Beryllium can occur naturally in sapphire but at levels of <1ppma. Beryllium diffused sapphire typically contains >10ppma, which is difficult to determine in a non destructive way. It is possible to utilize nuclear reaction analysis techniques to determine the beryllium content in a macroscopically non destructive way. Kinematically ideal reactions are Be(p,α) and Be(p,d) which, for Ep=0.5 to 0.9 MeV, exhibit distinct reaction product signatures well separated from other proton induced reactions in aluminium or oxygen. Due to the lack of comprehensive cross section data for the Be(p,α) and Be(p,d) reactions in the energy range of interest, a series of measurements were made at the Van de Graaff accelerator facility at Necsa to create a new data base. A further outcome of these measurements was a deviation in reported values for the non-Rutherfordian proton back-scatter cross section. These new data bases, which extend to Ep=2.6MeV, can now facilitate a procedure for determining beryllium content in sapphire. © 2011 American Institute of Physics.
De Beer F.C.,NECSA |
De Beer F.C.,North West University South Africa
Journal of the Southern African Institute of Mining and Metallurgy | Year: 2015
A number of important areas in nuclear fuel cycle, at both the front end and back end, offer ideal opportunities for the application of nondestructive evaluation techniques. These techniques do not only provide opportunities for non-invasive testing of e.g. irradiated materials, but also play an important role in the development of new materials in the nuclear sector. The advantage of penetrating radiation used as probe in the investigation and testing of nuclear materials makes X-ray and neutron radiography (2D) and tomography (3D) suitable for various applications in the total nuclear fuel cycle. The unique and different interaction modes of the two radiation probes with materials provide several opportunities. Their complementary nature and non-destructive character makes them most suitable for nuclear material analyses, analytical method development, and the evaluation of the performance of existing nuclear material compositions. This article gives an overview of the X-ray and neutron radiography/tomography applications in the field of nuclear material testing, and highlights a few of the success stories. Several selected areas of application in the nuclear fuel cycle are discussed to illustrate the complementary nature of these techniques as applied to nuclear materials. © The Southern African Institute of Mining and Metallurgy, 2015.
World Nuclear Association 35th Annual Symposium - The Nuclear Resurgence: Fulfilling Our Potential | Year: 2010
The South African government took an in-principle decision to convert the SAFARI-1 research reactor to LEU fuel in 1999. This was fully implemented in 2009, followed by a conversion to LEU target plates for radioisotopes production in 2010. The first shipments of such product to international customers took place in July 2010. Full conversion has not been without significant technical hurdles, but nevertheless constitutes an important step towards freeing the world of HEU-based production processes, in line with commitments made by heads of state at the April 2010 Nuclear Security Summit in Washington. It is expected that regulatory systems in countries purchasing significant quantities of radioisotopes will respond by giving preferential treatment to LEU-origin products.