INTERNAL STRESSES IN THE MANUFACTURE OF NUCLEAR REACTOR PRESSURE VESSELS

The importance of the influence of internal (inherent) stresses on the operation ability and on manufacture of large reactor pressure vessels is reported. Methods of measurement of internal stresses in the vessel wall are enumerated and the most convenient method is indicated for given purpose. Further the results of internal stresses measurements in welded rings of a cylindrical wall of a reactor vessel using hand and electroslag welding methods are reported. Experimental results of internal stress investigation are analysed and compared with theoretical calculations. Calculation difficulties and the necessity of evaluation of internal stresses-limiting values for larger vessels with their danger of brittle failures in welding joints, are indicated as well. (auth)