Comprehensive examination of the technical state of the metal of fittings of power units of nuclear power plants

We describe the methods and present the results of an examination of removable elements of fittings of two power units of the Rovno Nuclear Power Plant after 10 and 13 years of operation. It was discovered that, after the indicated periods of operation, the technical state of these elements was satisfactory and the material of the rods had no serious defects or other types of damage that could restrict the possibility of their subsequent operation. According to the regulations accepted in nuclear power engineering, the operating modes of fittings realized at nuclear power plants are light-duty as far as the number of loading cycles is concerned. Therefore, the degree of local fatigue damage to the metal of the rods does not reach its critical value. The outlined procedure of examination of removable elements of fittings is comprehensive. It is completed by low-cycle fatigue testing of the damaged metal and enables one to perform an adequate analysis of the possibility of subsequent trouble-free operation of the corresponding equipment. © 1998 Plenum Publishing Corporation.