BAM Forschungsberichte ohne Nummerierung
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- 2014 (2) (entfernen)
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- Auto ignition temperature (1)
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Mechanical drop test scenarios for Type B (U) packages according to the IAEA regulations have to be carried out onto the so-called “unyielding target” (usually with cask impact limiters) and onto the puncture bar respectively. They are predefined and do not require any further investigation of scenarios that really could happen on transportation routes. Cask accident scenarios in the framework of approval procedures for interim storage sites are derived from a detailed analysis of the handling procedures necessary from arrival of cask at the site to its storing position.
In that case, casks are usually handled without impact limiters. Dependent on possible drop heights, drop positions and floor properties, conservative cask accident scenarios are derived for further safety proofs. According to the mechanical assessment concept of the considered approval procedure numerical calculations have to be provided by the applicant to demonstrate mechanical cask safety. Stresses and strains in the cask body as well as in the lid System have to be identified and assessed. Using the example of a 3-mvertical-drop of a transport and storage cask for spent fuel elements onto the floor construction made of damping concrete covered by screed, BAM developed a finite element model. The finite element code ABAQUS/Explicit™ was used. Results of experimental investigations are not available. Therefore parameter studies are necessary to identify the sensitivity of the finite element model to significant Parameters and to verify the finite element models according to the requirements of the Guidelines for the Numerical Safety Analyses for the Approval of Transport and Storage Casks for Radioactive Materials (BAM GGR-008). The paper describes the modeling of the material behavior and attachment of bottom side cask components. Questions concerning the modeling of a crack length limiting reinforcement in the screed layer are discussed. The influence of the mesh density of the screed layer and its strength is considered as well. Finally, the developed finite element model can be used for a numerical safety assessment. It can help to understand the complex mechanisms of the interaction between the cask components and floor construction.
For the classification, safe handling and use of chemicals, special standardised test methods have been developed and are used worldwide. Safety experts must be able to fully rely on the precise execution of the respective laboratory tests and assessments. In this context interlaboratory tests (round robin tests, interlaboratory comparisons / intercomparisons) are a crucial element of both the further development and improvement of the methods and of a laboratory's quality system. Participation in interlaboratory tests is explicitly recommended by the standard ISO/IEC 17025. This document reports on the results of the interlaboratory test 2012-2013 on the test method EN 14522:2005 “Determination of the auto ignition temperature of gases and vapours“ / IEC 60079-201, part 7 ”Method of test for auto-ignition temperature”. The auto ignition temperature is an important safety characteristic for explosion protection and prevention. It is the basis for classifying substances and explosion protected equipment into temperature classes. Because safety characteristic data are not a pure substance constant but a figure which denotes a special property of the substance, the determination methods are standardised. Currently EN 14522 and IEC 60079-20-1, part 7 are under revision with the aim to combine both to a standard accepted worldwide. An important part of the standard is the laboratory’s verification of their apparatus and procedure. To base this forthcoming standard on reliable and up-to-date verification data an interlaboratory test appears as the method of choice. The verification data given in the recent issues of the standards are based on comparison measurements which date back to a long time ago and did not include automated apparatuses.