The Stress Analysis And Assessment Research Of The Antiseismic Pipeline â…¡ In China Advanced Research Reactor (CARR)

China Advanced Research Reactor (CARR) cooled and moderated by light water and reflected by heavy water is of inverse neutron trap design and of tank type, CARR is a all-purpose and high-powered research reactor for meeting the need of science and technology development in the 21st century, which primary capability index approach or reach the international advanced level of current research reactors. The functions of the secondary cooling water system(SCS) of CARR is to transmit the heat transferred by coolant system and other systems during normal operation and anticipative accidents to the ultimate heat sink, SCS is charged with the role that insure the equipments be cooled effectively on all cases.This paper firstly carried through the stress analysis and assessment of SCS, the stress analysis is fulfilled and the results can be used by CARR; then according to the correlative research and development pulse at home and overseas, the research are carried through encircling SCS mainly including the codes applications analysis and the anti-seismic analysis(involving the uncoupling analysis,the analysis of the relations between damping ratio and frequency,the analysis of the floor response spectrums and the analysis of the rigid cut-off frequency), the conclusions and suggestions are brought forward at last.(1) SCS stress analysis and assessment. The calculating of SCS (consisting of the inflow system and the outflow system) is carried through aiming at the original collocation of the piping and supports and hangers. The nozzle loads exceed the allowable values, parts of the node stresses of the outflow system can't satisfy the requiring of the codes, the series measures to be taken to reduce the nozzle loads and the node stresses.The inflow system: the rigidity of the inflow piping is very large, the great thermal thrust is the main cause of the nozzle loads exceeding the allowable values. Using the transferring speciality of the thermal expansion along the axes of the pipe the axes restraints are set on the pipes to restrict the passing of the thermal expansion to the equipments so as to reduce the pipe thrust.The outflow system: the flexibility of the outflow piping is very large, the seism loads occupy the great proportion among the composing of the nozzle loads, the fixation supports and hangers are set on the pipelines to increase the rigidity and the anti-seismic ability so as to reduce the nozzle loads. But the thermal stress of the piping nodes increase with it too, the snubbers can resist the seism without causing the increasing of the thermal stress, but the costly expenditure limits their applications. It is very economical to reduce the nodes stress by adjusting supports and hangers. The idiographic measures are selecting the logical types and restraint directions of supports and hangers, making certain the appropriate installation positions and rigidity coefficients, the node stresses satisfy the demands of the codes without using the snubbers so that the economic costs are cut down. The adjusting of supports and hangers is a complicated and reduplicate process, the systemic stress level,the security and reliability of operation and the economic costs all have the osculating correlations with the correct selecting and logical setting of them.(2) The codes applications analysis. The codes applications analysis are carried through encircling SCS, the homology and differentia of the results of codes are gained. The homology: the methods and results for calculating thermal stress with all codes are very adjacent, the results of RCCM,ASME before 1980 are very adjacent too when calculating all stresses, but the potty windage is brought and the cause is discussed. The differentia: the methods and results for calculating the deadweight and seism stresses are very different, the deadweight and seism stresses values of ASME(after 1980) all increase too much comparing with that of the RCCM,B31.1,ASME(before 1980),which shows that the calculating principles and methods had been changed much.(3) The anti-seismic analysis.(i) the uncoupling analysis: The conclusions are drew by calculation. The stresses influence that the primary piping inflict to the thin piping is great, it is puny contrarily. (ii) the analysis of the relations between damping ratio and frequency: Using the damping ratio recommended by RG1.61 will get the conservative results, the results of N411 methods increase the economy capability on the base of guaranteeing the security.(iii) the floor response spectrum analysis: The results of the multiple floor response spectrums will be more accurate than that of the single floor response spectrums.(iv) the cut-off frequency analysis: According to the theory deducing, the results of PIPESTRESS, the characteristic of the floor response spectrum curves afforded by Tsinghua university, It prove that the "20Hz " can be used as the cut-off frequency whencalculating the anti-seismic piping stress in CARR.