[en] Heating rods have been tested under cold conditions without pressure and under working conditions. The characteristic of defects and measures to assure the quality have been found. Two types of heating rods, 'Siemens Makrorohrheizkoerper' and 'Philips Rod Heater', have been tested. Both types are qualified as heating rods for pressurizers after considering the requirements corresponding to the results of the tests. In the future, heating rods of the type 'Rod Heater' will be used; this type has rendered possible the simplification of the pressurizer design because of its working assurance. (orig.)