[en] Nuclear techniques have a long history of application in the coal industry, during exploration and especially during coal preparation, for the measurement of ash content. The preferred techniques are based on X- and gamma-ray scattering and borehole logging, and on-line equipment incorporating these techniques are now in world-wide routine use. However, gamma-ray techniques are mainly restricted to density measurement and X-ray techniques are principally used for ash determinations. They have a limited range and when used on-line some size reduction of the coal is usually required and a full elemental analysis is not possible. In particular, X- and gamma-ray techniques are insensitive to the principal elements in the combustible component and to many of the important elements in the mineral fraction. Neutron techniques on the other hand have a range which is compatible with on-line requirements and all elements in the combustible component and virtually all elements in the mineral component can be observed. A complete elemental analysis of coal then allows the ash content and the calorific value to be determined on-line. This paper surveys the various nuclear techniques now in use and gives particular attention to the present state of development of neutron methods and to their advantages and limitations. Although it is shown that considerable further development and operational experience are still required, equipment now being introduced has a performance which matches many of the identified requirements and an early improvement in specification can be anticipated