[en] This review is intended to cover the fundamentals of physics, electronics and data handling techniques as they apply to the problem of the use of ultrasonics in nuclear safeguarding. A number of individual aspects of the total problem are first discussed and the advantages and problems raised by these are set out. The basis of the specification of ultrasonic probes for safeguarding purposes is then discussed. Finally some tentative conclusions are drawn. In its present form the document is intended as a listing of potential problems with some ideas for their solution. It is recognised that some problems are currently under investigation but it is assumed that it is better to provide as comprehensive a list as possible rather than to attempt to select only those problems which may not have yet been addressed. (author)