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Schindler H.-J.,Materials Tec AG | Kalkhof D.,Swiss Federal Nuclear Safety Inspectorate
13th International Conference on Fracture 2013, ICF 2013 | Year: 2013

The inherent scatter of fracture toughness of ferritic steels in the brittle-to-ductile transition regime require statistical methods to be applied for testing and evaluation. However, for engineering purposes lower bounds of KIc such as the ASME-reference curve are often preferred since they allow deterministic worst-case predictions to be made. So the question is how to derive lower bounds of a quantity that is governed by weakest-link-statistics. Actually, neither the MC-approach nor the empirical ASME-reference curve deliver well-founded lower bounds for components of relatively small thicknesses. A theoretical model is suggested to fill this gap. The key element of the approach is the hypothesis that the weakest-link-effect is saturated at a certain thickness. The corresponding upper limit of size-dependence turned out to be close to the minimum thickness required for plane-strain conditions at the crack-front. The derived mathematical relations enables KIc to be calculated from KJc as measured on a smaller specimen. In reverse, from a lower-bound KIc as provided by the ASME-code a thickness-dependent lower bound of KJc can be obtained. The proposed model is shown to yield predictions that are consistent with experimental data as well as with the ASME-lower bound. Copyright © (2013) by International Conference on Fracture.

Von Hagke C.,Helmholtz Center Potsdam | Von Hagke C.,California Institute of Technology | Cederbom C.E.,Swedish Geotechnical Institute | Oncken O.,Helmholtz Center Potsdam | And 3 more authors.
Tectonics | Year: 2012

The evolution of the Central Alpine deformation front (Subalpine Molasse) and its undeformed foreland is recently debated because of their role for deciphering the late orogenic evolution of the Alps. Its latest exhumation history is poorly understood due to the lack of late Miocene to Pliocene sediments. We constrain the late Miocene to Pliocene history of this transitional zone with apatite fission track and (U-Th)/He data. We used laser ablation inductively coupled mass spectrometry for apatite fission track dating and compare this method with previously published and unpublished external detector method fission track data. Two investigated sections across tectonic slices show that the Subalpine Molasse was tectonically active after the onset of folding of the Jura Mountains. This is much younger than hitherto assumed. Thrusting occurred at 10, 8, 6-5Ma and potentially thereafter. This is contemporaneous with reported exhumation of the External Crystalline Massifs in the central Alps. The Jura Mountains and the Subalpine Molasse used the same detachments as the External Crystalline Massifs and are therefore kinematically coupled. Estimates on the amount of shortening and thrust displacement corroborate this idea. We argue that the tectonic signal is related to active shortening during the late stage of orogenesis. © 2012. American Geophysical Union. All Rights Reserved.

Sentis M.L.,Swiss Federal Nuclear Safety Inspectorate
Nuclear Technology | Year: 2014

FORGE (Fate of Repository Gases) is an international research project supported by funding under the European Commission FP7 Euratom program and lasting four years from 2009 to 2013. The project is dedicated to understanding gas generation and migration as part of the quantitative assessment of a geological repository for radioactive waste. Within the FORGE project, Work Package 1 is dedicated to numerical modeling of a two-phase flow system (hydrogen gas due to corrosion and groundwater) in a geological repository for radioactive waste. Several benchmark exercises were proposed that cover the modeling of a deep geological repository from the disposal cell scale to the repository scale with different codes. During the definition of the exercises, special emphasis was given to the roles of the excavation-disturbed zone and of the interfaces between materials, which could act as a conduit for preferentialflow. Some changes were made in the TOUGH2 code to enable the implementation of the prescribed conditions, models, and parameters of the benchmark. The results of the calculations performed with different codes show that TOUGH2 gives comparable results under the numerically challenging conditions defined in the exercise. Some differences were observed resulting from the use of different codes and also from some simplifications in the parameters and models adopted by the participating teams. In this paper, the cell-scale benchmark exercise and the results obtained by the Swiss Federal Nuclear Safety Inspectorate (ENSI) with TOUGH2 will be described, together with some difficulties encountered during the simulation, e.g., convergence problems. The results of other teams participating in the benchmark are in good agreement with the ENSI results.

Bucher B.,Swiss Federal Nuclear Safety Inspectorate
Radiation Protection Dosimetry | Year: 2014

During an international intercomparison exercise of airborne gamma spectrometry held in Switzerland 2007 teams from Germany, France and Switzerland were proving their capabilities. One of the tasks was the composite mapping of an area around Basel. Each team was mainly covering the part of its own country at its own flying procedures. They delivered the evaluated data in a data format agreed in advance. The quantities to be delivered were also defined in advance. Nevertheless, during the process to put the data together a few questions raised: Which dose rate was meant? Had the dose rate to be delivered with or without cosmic contribution? Activity per dry or wet mass? Which coordinate system was used? Finally, the data could be put together in one map. For working procedures in case of an emergency, quantities of interest and exchange data format have to be defined in advance. But the procedures have also to be proved regularly. © The Author 2014. Published by Oxford University Press. All rights reserved.

Bucher B.,Swiss Federal Nuclear Safety Inspectorate | Rybach L.,ETH Zurich | Schwarz G.,Swiss Federal Nuclear Safety Inspectorate
Kerntechnik | Year: 2012

Annually since 1989, biannually since 1994 the sites of the Swiss nuclear facilities (4 power plant sites, a nuclear research institute and a waste storage facility) are surveyed flying the same survey lines by airborne gamma ray spectrometry. The equipment and the data processing software used for those surveys was built and developed at the Institute of Geophysics, ETH Zurich. For mapping the ground radiation around the nuclear facilities a pixel representation and a modified Spectrum Dose Index (SDI) method is used. In the search for long-term trends the local dose-rates are calculated first and in turn the net dose rates over the time span 1992-2010. So far no significant change in the radiation levels was detected over the last 18 years outside of the fenced sites of the nuclear facilities, except for the operation of an industrial radiation facility in 1995. © Carl Hanser Verlag, München.

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