Nuclear waste is a toxic, radioactive, and long-lasting byproduct to the generation of nuclear energy. It must be disposed of safely and ethically, ensuring that it will be isolated from the biosphere for millennia. Although burying nuclear waste in an underground repository has been extensively researched since the concept was proposed in the 1950s, the safe and ethical disposal of nuclear waste has not been successfully demonstrated anywhere in the world. There are two sets of challenges: 1) the technical difficulties involved in emplacing these radioactive materials underground and ensuring that they will remain there trapped for millennia, and 2) the social barriers arising from communities opposing the burial of nuclear wastes in their vicinity. Most of the technical research conducted thus far has been concerned with the behavior of the waste thousands to millions of years into the future, after it has been permanently emplaced underground. Social science research has largely focused on getting communities to accept repositories. Neither stream has studied the challenges of the near long-term, the period that could last several decades, between the start of construction of a hypothetical repository and its sealing off, when wastes are being transported and placed underground. How the challenges of the near long-term are addressed could affect both public perceptions and the longer term performance of nuclear waste repositories.