When civilian nuclear power plants in the United States of America (USA) were initially constructed, the assumption was that the Federal government would ultimately take title to the used nuclear fuel (UNF), relieving nuclear power plant operators of the burden of managing UNF at their sites. As we all know, this has not been the case. Thus, the nuclear industry in the USA has been challenged with finding a solution for storing UNF on nuclear plant sites for long periods of time.