Calculation of Dose Rates at the Surface of Storage Containers for High‐Level Radioactive Waste
Abstract In several countries, the high‐level radioactive waste that will be disposed of in deep geological formations has to be retrievable for a certain time. Since 2010, retrievability is required for the operation phase of a repository also in Germany. Depending on the effort and the feasibility of remote handling, a certain exposure of the involved employees to ionising radiation is caused. The estimation of the exposure requires the knowledge of the inventory of radionuclides and the radiation field around the storage containers. This paper focuses on German concepts for final storage casks for the drift emplacement in rock salt for both spent fuel rods and high‐active waste (HAW) coquilles. Calculations of dose rates at the surfaces of the casks are presented. The calculations show that the gamma radiation of fission and activation products can be efficiently shielded by materials like cast iron or low‐alloyed steel. Ductile cast iron, however, has a positive influence on the neutron moderation because of the high carbon content. The shielding of the neutron radiation strongly depends on the quantity and position of the polyethylene (PE) rods which are used as neutron moderator. PE has unfavourable features at elevated temperatures that can be reached in a repository for high‐level waste. The simulations show that TiH2 is a promising alternative material for the shielding of neutron radiation. The current assumption that a final storage cask for HAW coquilles has the same outer dimensions as the cask for spent fuel rods will lead to unacceptable dose rates at the side wall. An increase of the diameter is necessary to provide sufficient shielding. Graphite insets in the cask interior lead to a considerably lowered dose rate.
Laser welding of plastics
Abstract: Lasers may be used for rapid and reproducible welding of plastics. The principles of plastics welding and direct and transmission laser welding for plastics are described. The equipment variations and process parameter effects are discussed and guidance for practical application of the technique is provided. Typical application areas are summarised.
A numerical study on liquid ring motion and fragmentation for the initial process of liquid explosive dispersal
For the explosive dispersal on liquid fuel of FAE technique, the expansion of gaseous detonation products, axisymmetric radial extension and fragmentation of a liquid ring were analyzed, then corresponding models were established. By those models coupled, the numerical simulation on motion and fragmentation of the liquid ring exerted by strong action was carried out. The results computed show that the models established are feasible, and present study can offer initial conditions for the numerical simulation on the process of liquid secondary breakup and gas-liquid mixing.