| Zdroj: |
Packaging, Transport, Storage & Security of Radioactive Materials; 2007, Vol. 18 Issue 1, p11-18, 8p, 9 Diagrams, 2 Charts |
| Abstrakt: |
The US Nuclear Regulatory Commission (NRC) is responsible for licensing commercial spent nuclear fuel transported in casks certified by NRC under the Code of Federal Regulations (10 CFR), Title 10, Part 71. Both the International Atomic Energy Agency regulations for transporting radioactive materials, and 10 CFR 71·73 require casks to be evaluated for hypothetical accident conditions, which includes a 9 m (30 ft) drop impact event onto a flat, essentially unyielding, horizontal surface, in the most damaging orientation. This paper examines the behaviour of one of the NRC certified transportation casks, the TN-68, for drop impact events. The specific area examined is the behaviour of the bolted connections in the cask body and the closure lid, which are significantly loaded during the hypothetical drop impact event. Analytical work to evaluate the NRC certified TN-68 spent fuel transport cask for a 9 m (30 ft) drop impact event on a flat, unyielding, horizontal surface, was performed using the ANSYS and LS-DYNA finite element analysis codes. The models were sufficiently detailed, in the areas of bolt closure interfaces and containment boundaries, to evaluate the structural integrity of the bolted connections under 9 m (30 ft) free drop hypothetical accident conditions, as specified in 10 CFR 71·73. Evaluation of the cask for puncture, caused by a free drop through a distance of 1 m (40 in) onto a mild steel bar mounted on a flat, essentially unyielding, horizontal surface, required by 10 CFR 71·73, was not included in the current work. Based on the analyses performed to date, it is concluded that, even though brief separation of the flange and the lid surfaces may occur under some conditions, the seals would close at the end of the drop events, because the materials remain elastic during the duration of the event. [ABSTRACT FROM AUTHOR] |
