PACKAGE TESTING OF A DUAL PURPOSE CASK FOR SNF FROM GERMAN RESEARCH REACTORS

摘要

A new dual purpose cask design was developed forthe safe transport and interim storage of spent fuelelements of German research reactors. In the frameworkof the safety assessment within the package approvalprocedure the Bundesanstalt für Materialforschung und –pruefung (BAM) as competent authority performed a seriesof drop tests according with the IAEA TransportRegulations.The package consists of a cylindrical thick-walledductile cast iron cask body closed by a double lid systemwith metallic seals. A lid and bottom sided impact limiterconsisting of a wood/steel construction limit themechanical impact loading. The full-scale test specimenwas equipped with a basket and assembled with dummyfuelelements. The package and test specimen,respectively have a total mass of approximately 24 metrictons.The mechanical test program included three 9m freedrop tests, in horizontal, vertical and oblique caskorientation onto the lid system. Additionally, a 1mpuncturebar drop test followed the horizontal drop test toconsider an IAEA-drop test sequence. The horizontal andvertical drop tests were performed at a temperature ofminus 40℃. During the oblique drop test the upperimpact limiter was heated up to +80℃. The tests wereconducted onto an unyielding target, fulfilling the IAEArequirements.The test specimen was considerably instrumentedwith strain gauges and accelerometers. Transient strainsat selected locations of the inner and outer containerwalls, of the primary and secondary lid, as well as of thecorresponding lid bolts were measured during the droptests. Furthermore, decelerations in different locations atthe cask body and the lids were measured. The complexgeometrical deformation of the impact limiters due to theimpact were determined by optical 3D- measurements.Before and after the drop tests the leakage rate of the lidsystem was determined by helium leakage testing.The experimental results contribute to the evaluationof the package response to mechanical tests,demonstrating safety under normal and accidentconditions of transport and especially to the verificationof the dynamic finite-element model of the package usedin the package design safety report.