The largest fraction of all energy consumed by society is in the form of heat at a temperature below 150 deg. C, and the use of nuclear energy to provide this sort of energy has been examined for the past several years. Accordingly the IAEA has been involved in related activities ever since the various technical approaches were first discussed in the late 1970s within the Nuclear Power Programme. A number of meetings, such as Technical Committee meetings and Advisory Group meetings have been held, and their results have usually been published in IAEA-TECDOCs, the last of in 1991. Refs, figs, tabs.