Long-term operation of Russian NPPs taking into account the actual loading of passive components
The paper considers provision of strength and structural integrity for safety relevant passive NPP components - pipelines and equipment - in long-term operation of NPP units. The methods of determining the actual load parameters during equipment installation, adjustment and commissioning are considered. The application of the acoustoelasticity method, which provides measurement of mechanical stresses arising as a result of technological operations, will allow to identify implicit installation preloads and assess their impact on ensuring the design life of pipeline systems, including the equipment installed. Recommendations are given for application of the acoustoelasticity method on NPP units under construction as a fist priority. At the objects of application of the acoustoelasticity method for the construction of the Unit1 of Kursk NPP-2, noted above (ECCS, CS, steam and feed water pipelines), at the present time, in accordance with the certified measurement procedure (CMP), it is possible to reveal implicit installation preloads only at temperatures not higher than 55ºC. Monitoring the actual load level in the "as built" state will be a reliable guarantee of safe operation of Kursk NPP-2 pipelines according to the criteria of strength and structural integrity.