Holtec International said last week its HI-STAR ATB-1T cask design for nuclear waste transport successfully passed the Nuclear Regulatory Commission’s 30-foot “free drop” test.
According to Holtec, the HI-STAR ATB-1T is the first “large, rectangular” cask for high-level waste to pass the test without any breach of containment boundary. The tests require that casks maintain radiation blockage when dropped from 30 feet onto “an essentially unyielding surface.” The NRC and international regulations require that the casks receive “maximum damage” from impact of the drop.
“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 with several corners, facets and edges that render it vulnerable to a crushing impact loading,” Holtec stated.
The HI-STAR ATB-1T cask, weighing about 120 tons with payload, does not have an impact limiter to cushion impact, further separating it from cylindrical fuel transport casks. To minimize crew doses, the HI-STAR ATB-1T cask are also fitted with a connect-disconnect-controlled cask locking system, instead of a conventional bolted lid, according to Holtec.
The tests involved three successive drops with a quarter-scale model of the cask, which is manufactured by the Holtec Manufacturing Division and is used by the Sandia National Laboratories in Albuquerque, N.M.
“To the delight of the assembled engineers, the cask, although challenged by the three successive direct collisions that included a top down oblique drop, a center of gravity over corner (CG over corner) drop, and a puncture drop test, met the structural sufficiency criterion and sustained no damage to its containment boundary or dislodging of its closure lid,” the announcement said.
Holtec said it hopes the HI-STAR ATB-1T becomes “a reliable workhorse for nuclear plants, especially those undergoing decommissioning.”
