[en] Based on the Siempelkamp activities in the field of the development of prestressed cast iron pressure vessels, a cooperation contract concerning the development of the Prestressed Cast Iron Pressure Vessel (PCIV) for high temperature reactors (HTR) has been signed between: Gesellschaft fuer Hochtemperatur Reaktortechnik mbH (GHT), Hochtemperatur Reaktorbau GmbH (HRB), Steinmueller, and Siempelkamp. The research and development program for this type of PCIV is sponsored by the Ministry for Economics and Transportation of the state of Northrhine-Westphalia. The objects of the R and D program are: - Fully worked out construction plans. - Demonstration of the decisive economic advantages of this new type of vessel. - Plans designed to meet the requirements of licenzing authorities. - A preliminary safety report. (Auth.)