Inelastic response of metallic impact limiters

Energy mitigators on some light water reactor (LWR) spent fuel shipping casks and conceptual designs for liquid metal fast breeder reactor (LMFBR) spent fuel shipping casks rely on the inelastic behaviour of metallic plate-like structures. A program was undertaken to investigate the response of mitigators to hypothetical shipping accidents with parallel experimental and theoretical studies. The theoretical studies consist of performing large deformation three dimensional transient dynamic analysis on several metal fin designs and correlating the results with the experimental results. The newly developed computer program WULFF was used. Testing of scale model fin specimens was performed at SLA's drop table facility. The test specimens are mounted on a force transducer and this assembly is bolted to the stationary bottom table. Extra weights are added to the drop table so that the total energy at impact is sufficient to cause large plastic deformation in the specimens. Accelerometers mounted on the drop table and the data from the force transducer are used to compute the energy absorbed during the test. Also framing camera coverage was used to observe the specimen deformation as it develops. The results of the theoretical analysis and experimental program can be used by designers responsible for impact limiters on spent fuel shipping casks. Without data to design impact limiters the integrity of the cask under accident conditions can be questionable. (Auth.)