Apparatus for the production of carbon dioxide from limestone includes a nuclear reactor (10) for generating heat and a rotary kiln (12). The rotary kiln (12) has an inlet (28) for the introduction of limestone and an outlet (30) for the release of carbon dioxide. A heat transfer arrangement is provided for transferring heat from the nuclear reactor (10) to the interior of the rotary kiln (12). The heat transfer arrangement includes feed and return primary conduits (17,18) for passing a heat transfer fluid (14) through the nuclear reactor (10) so that heat may be extracted from the nuclear reactor (10) for transfer to the interior of the rotary kiln (12). Limestone in the rotary kiln (12) is thereby heated to a temperature sufficient for the release of carbon dioxide.