• Fortino, Stefania
• Kuutti, Juha
• Heinonen, Jaakko
• Hakola, Ilkka

Abstract

In the Finnish final disposal plan the spent fuelcanister will be transferred to an undergroundrepository at 400-450 meters below ground surface by avertical lift. This paper considers the postulatedaccident scenario where the disposal canister fallsduring transportation. In case of free fall, the 25-tondisposal canister can reach a velocity of 90 m/s beforeimpacting the shock absorber. The shock absorberis designed to consist of cohesionless granularlightweight expanded clay aggregate (LECA) material thatwill decelerate the disposal canister in a controlledmanner. By utilizing the IMPACT test facility at VTTTechnical Research Centre of Finland, laboratory scaleshock absorber tests have been carried out. A rigid scalemodel of the disposal canister was shot into a shockabsorber pipe in a horizontal setting with a realisticvelocity. A total of 21 tests have been carried out withvelocities ranging from 38 m/s to 97 m/s using disposalcanister scale models with diameters from 63 mm to 150mm. Other dimensions in the testing were scaledcorrespondingly. The aim of the experiments and numericalanalysis was to assess the behavior of LECA as shockabsorbing material and determine both the required depthof the shock absorber and loading subjected to thedisposal canister. LECA used in the tests had grain sizeof 4-10 mm. The test results show a clear trend ofpenetration distance increasing as the impact velocityincreases and some scatter. No distinctive effect of thetest scale was seen in the results.

Topics

• surface
• grain
• experiment
• impact test