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- Ageing (9)
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- 3 Gefahrgutumschließungen; Energiespeicher (125) (entfernen)
On the basis of a lot of investigation on the spectral sensitivity of photo degradation of plastics and on the underestimated influence of temperature and relative humidity on degradation processes a new type of weathering device was presented at the end of the seventies:
It was a combination of a radiation source with fluorescent UV lamps and a precise climatic cabinet.
The radiation emission from a combination of four different types of fluorescent UV lamps was superimposed on the specimen surfaces in the climatic cabinet to match the UV part of solar radiation as closely as possible. Air temperature was controlled to within ± 1 °C, and relative humidity to within ± 5 %RH.
As the lamps’ emission is focussed on the UV range almost no radiation heating of the sample occurs. Therefore, the temperature of the sample, which is the quantity of consideration for the degradation, is nearly identical with the chamber’s air temperature, which is the quantity to be controlled. Also, therefore, high humidity can be obtained on the sample surface. The limitation of the emission to the UV range is sufficient for the study of the polymer matrix.
This type of weathering device offers an exactness of microclimatic control of the sample’s surface, which should be a standard for weathering devices. Even now it is the only weathering device which generates pure relative humidity (without aerosol).
Liquefied Hydrogen (LH2) or Liquefied Natural Gas (LNG) establish themselves as important energy carriers in the transport sector. Its storage requires tanks with Thermal Super Insulations (TSI) to keep the transported fluid cold. TSI has proven itself in various applications over a long time, but not in the land transport sector, where accidents involving collisions, fires, and their combination are to be expected. The focus of this study is to investigate the behavior of different types of TSI when exposed to a heat source that represents a fire. Therefore, a High-Temperature Thermal Vacuum Chamber (HTTVC) was used that allows the thermal loading of thermal insulation material in a vacuum and measuring the heat flow through the TSI in parallel. Within this study, 5 samples were tested regarding 3 different types of MLI, rock wool, and perlites. The thermal exposure caused different effects on the samples. In practice, this can be connected to the rapid release of flammable gases as well as a Boiling Liquid Expanding Vapour Explosion (BLEVE). These results are relevant for the evaluation of accident scenarios, the improvement of TSI, and the development of emergency measures.
The potential benefits to the roll stability of a road tanker, derived from using a convex-bottom tank, instead of a concave-bottom one, are assessed. The convex-bottom tank consists of a modified elliptical figure to which the concave bottom is substituted by a convex one. The concave-bottom consists of an elliptical shape. Static and dynamic analyses are performed, for which the proposed shape revels enhancements on the order of 10%. The static rollover stability factor, and the lateral load transfer ratio, are used as performance measures for the static and the dynamic analysis, respectively. The dynamic analysis derives from a simplified model, for which the sloshing mass is substituted by a calibrated simple pendulum. Other potential benefits of the proposed tank shape are discussed, including a reduction in the aerodynamic drag, and a longer life for the vehicle components.
The excellent mechanical properties of elastomer seals at a wide range of temperatures as well as their high versatility and recovery potential under several load conditions make these materials well suitable for the application in containers designed for transport and disposal of negligible heat generating radioactive waste. While a seal exchange at defined intervals is typical in many conventional applications, it is impossible or at least hard to perform when principles of minimization of radiation exposure have to be considered which prohibit an avoidable cask handling. An extensive knowledge of the change of the elastomer properties during aging and the availability of reliable end-of-lifetime criteria to guarantee the safe enclosure of the radioactive material for the required time are mandatory. As BAM is involved in most of the national cask licensing procedures and in the evaluation of cask-related long-term safety issues, great efforts have already been made and are still ongoing to scientifically support this task.
Among other representative types of elastomers, specimen made from ethylene propylene diene rubber (EPDM) were tested before, during and after aging to capture the with respect to application most important of their complex mechanical properties.
Exemplary results of these investigations were used to calibrate material models implemented in the commercial finite element software ABAQUS/Standard®. The finite element model already presented in previous works uses a sequential temperature displacement coupling. The calculated compression stress relaxation (CSR) and compression set (CS) values do satisfactorily match the experimental results.
In many investigations performed at BAM both values (CSR and CS) were identified as key indicators of elastomer’s long-term performance.
However, the possibility to correlate these equivalent indicators with performance values such as tightness and leakage rate, measurable in the mounted state, is an important goal of our future work. In the presented study the ABAQUS® feature of “pressure penetration” is introduced in the suggested finite element model for this purpose. It provides the possibility to simulate the penetration of a gas into a possible gap between flange and O-ring causing an opening of a leakage path. Three dimensional and axis-symmetric finite element models were generated to represent flat and grooved flanges of different dimensions.
The sensitivity of the feature to several input parameters is investigated and the observed behavior of the O-ring is correlated with the results of performed leakage tests.
GPS-data based calculation scheme for assessing, in real-time, the level of safety exerted during driving, has been described and used. The several variables involved considered the main factors that lead to road mishaps, including the speed, the acceleration and the effects that these variables have on the vehicle when it is negotiating a turn. The performance measure combines three individual performance outputs: speed, acceleration and a hybrid performance measure considering the speed, the acceleration and the change in latitude/longitude. The measures are designed in such a way that weighting factors can be calibrated in order to establish certain critical parameters. On the other hand, the terms in the equations preclude any division by zero of the involved ratios. On the other hand, the simplicity of the equations makes it possible to carry out the assessment in real time. The use of the resultant performance measure to a relatively long path, together with its current average value, indicates that the safe performance of the driving changes with time, and that, for the selected values of the calibration constants, the traveling speed dominates the overall safety performance of the driving. Furthermore, the different calibration constants provide the possibility of considering different types of hazmat carrying vehicles. While many other formulation components could be integrated into the performance measure, this three-component performance measure could be used to assess the driving of a hazmat-carrying vehicle, in order to detect and to prevent dangerous conditions, such as driver fatigue.
Finally, the implementation of the different performance measure formulations in a system such as the one described in the introduction of this paper, could be straightforward.
A testing rig for the measurement of the dynamic loads on the rails due to cargo sloshing,has been proposedin this paper. The system represents a scale-down approach that simulates astraightening maneuver of the railway car after negotiating a turn. As part of the experimental effort, a mathematical model was developed that, oncevalidated, will provide more insights about the potential effect of many other cardesign factors, on the level of stress developed in the raildue to the sloshing cargo.A fundamental output from the testing, will be the objective comparison between the railloads due toa sloshing and a non-sloshing cargo, together with a validated model that wouldallow parametric studies in relation withthe potential effect,of several track and carproperties,on the magnitude of the sloshing forces on the rail.
In accordance with the IAEA transport regulations, the design of special form radioactive material (SFRM) shall resist a severe transport accident without undue loss or dispersal of radioactive material. The safety assessment for design approval includes besides the program for physical tests (impact, percussion, bending and heat test) also the evaluation of the management system for design, manufacture, testing, documentation, use, maintenance, and inspection.
SFRM source design plus management system shall ensure, that every specimen of the approved design is able to survive the severe mechanical and thermal tests at any time of its SFRM-working life.
Due to the long-term use of SFRM designs in most cases, the assessment of the source ageing behavior is an important aspect in the approval procedure. Different fields of application imply a wide range of environmental conditions, from clean room atmosphere to highly aggressive industrial conditions. Besides of radioactive content, corrosion is a main factor for possible SFRM design degradation.
Although the IAEA Advisory Material SSG-26 already implies an indication of the need for considering ageing mechanisms, suitable amendments in the regulatory requirements of SSR-6 should be introduced to make the approval procedure more transparent and help to reduce rounds of questions by the authority. A supplementary requirement for considering of ageing mechanisms could be a helpful contribution to an international harmonization of the approval procedure.
This paper will describe major influencing factors to be considered to assess the ageing behavior of a SFRM design and will identify the need for a regulatory specification of a SFRM-working life as basis for the assessment of the SFRM design regarding time-dependent weakening. A proposal for an explicit requirement for consideration of ageing mechanisms in safety assessment of SFRM, which should be considered in the ongoing SSR-6 revision cycle, will be explained.
In accordance with the IAEA transport regulations Special Form Radioactive Material (SFRM) is either an indispersible solid radioactive material or a sealed capsule containing radioactive material.
The design of special form radioactive material has to resist a severe transport accident without undue loss or dispersal of radioactive material. The safety assessment for design approval shall include besides the required test program (impact, percussion, bending and heat test) also the evaluation of the management system for design, manufacture, testing, documentation, use, maintenance and inspection. The specified quality assurance measures have to assure, that every specimen of the approved design is produced in the same verified quality and every specimen must be able to survive the severe mechanical and thermal tests at any time of its working life.
Due to the long-term use of SFRM the consideration of ageing is an important aspect in the approval procedure by BAM, the competent authority for SFRM approval in Germany. Different fields of application imply a wide range of environmental conditions, from clean room atmosphere to highly aggressive industrial conditions. So, besides of radioactive content, corrosion is a main factor for possible design degradation.
This paper will describe major influencing factors to be taken into account to assess the ageing behavior of a SFRM design and will emphasize that there is a need for a regulatory specification of a SFRM-working life as basis for the aging evaluations.
The consideration of ageing mechanisms is with integration into the IAEA-requirements now obligatory for the design of transport packages. For packages intended to be used for shipment after storage the consideration of the effects of ageing mechanisms during storage in safety analyses and the implementation of corresponding instructions for operation and maintenance are required. Therefore, these packages have been maintained during storage in a manner that all requirements specified in the IAEA-requirements and in the applicable certificates of approval have been fulfilled.
BAM is the competent authority in Germany for evaluating the thermal and mechanical design of packages for the transport of radioactive materials. In this context, BAM also evaluates the aging mechanisms and aging effects occurring during the long-term storage period of such transport packages. BAM has developed a guideline for the implementation of ageing assessment and of the measures for ageing management into the approval procedure based on IAEA-requirements.
The goal of the presented paper is to introduce this guideline and the general approach for ageing management requirements and to describe the application to a specific package design. The type and amount of the ageing management not only depend on the use of the packaging, but also on the accessibility of the components that are considered in the ageing assessment. The different operating phases of a packaging are considered for the ageing assessment, such as loading, interim storage or transport.
The implementation of measures for ageing management is divided into three levels – systemic measures, package design related measures and documentation. The systemic measures are attributed to the general management system and define the whole activities for organization of ageing management like structure, responsibilities, documentation, reports and evaluation. The package design related measures are defined in an ageing management plan. These measures shall ensure that the anticipated changes of the package design under consideration of ageing effects still complies with the design approval specification. Therefore, an ageing surveillance program and, if necessary, a gap analysis program shall be developed. The ageing management documentation ensures the continuous documentation of the compliance of a specific package to the approved package design, comprising mainly records resulting from operation and surveillance.
Externalities of the road transportation are multidimensional in nature and involve the road-vehicle interaction under different environmental conditions. Estimating the pavement and vehicle damage potentials as a function of the condition sunder which such interaction takes place, is important to avoid accelerated or catastrophic damages in these systems. Such an assessing is crucial from the perspective of pricing the effects of the vehicle on the infrastructure and vice versa. The existing models for pricing such interaction, critically depends on gross average statistical models. In this paper, it is proposed a deterministic approach to realize such an assessment, based upon validated approaches for the pavement damage. The simulation scheme considers different degrees-of-freedom vehicle models, and a discrete asphalt pavement, that make possible the simulation of massive traffic situations on realistic road lengths.