[en] Activities in programs devoted to disposal of radioactive waste in deep geologic formations are reported. Research on borehole plugging and shaft sealing is emphasized. Past and current activities related to penetration sealing were assessed through an exhaustive literature review and contacts with industrial, governmental, and research organizations. Cited references are included along with a bibliography assembled for this study. Evaluation of literature reviewed and presentation of information obtained from personal contacts are summarized. Technical considerations for penetration sealing as related to nuclear waste isolation, but which may differ from conventional technology, are presented and research needs are identified