Industry’s First Large Rectangular Cask for Reactor-Related Waste Passes Successive 30 Foot “Free Drop” Tests Without Any Breach of Its Containment Boundary

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To earn the USNRC (or IAEA’s) certification, a transport cask must pass a series of “free drop” tests, in which a scaled replica of the loaded cask is required to be shown to maintain its radiation blockage capability substantially unimpaired, if dropped from a 30 foot elevation onto “an essentially unyielding surface.” Under the USNRC and international regulations, the cask’s orientation at impact with the target is required to be selected so as to induce maximum damage to the cask. For the HI-STAR ATB-1T cask (or HI-STAR 330), introduced to our readers in issue HH 30.16, the “free drop” tests were a particularly daunting challenge because, in contrast to a fuel-bearing transport cask which is cylindrical, HI-STAR ATB-1T has a large rectangular footprint (12 feet x 5.9 feet) with several corners, facets and edges that render it vulnerable to a crushing impact loading. Further, whereas cylindrical fuel transport casks are always outfitted with impact limiters, the HI-STAR ATB-1T cask (weighing 120 tons with its payload) has no impact limiter to cushion its impact upon its collision with the target. To minimize crew dose during loading and unloading evolutions, the HI-STAR ATB-1T cask is also equipped with an innovative quick connect/disconnect controlled cask locking system (CLS) in lieu of a conventional bolted lid.