Assessment and Management of Aging in Phenix Nuclear Power Plant

摘要

The combination of one or several processes of ruins canrninvolve the materials failure of a nuclear power plant. Thesernprocesses arise from the external agents action such as thernpressure, the mechanical efforts, the heat flows and thernradiations constitute the whole of the "actions" of thernsurrounding medium. The prolongation and the repetition ofrnthese effects can involve a deterioration of the machine.rnIn accordance with the decree of February 26, 1974, thernPWR operator must be firstly, sure that the system isrncontrolled according to the situations considered in the file ofrndimensioning and secondly, be able to know anytime the lifernof the equipment.rnThe physical phenomena which cause the structures ruin arernless complex in the PWR than in the SFR. In the SFR, thernhigh temperatures imposed on components for long periodsrncan involve a significant creep. In the course of time, thisrndeformations accelerate the release of fatigue cracks. Tornconsider the creep, the reactor lifespan is correlated at thernnumbers of thermals transients envisaged initially.rnTo realize the management of aging in Phenix power plant, itrnis necessary to carry out an individualized monitoring of thernstructures and not only on the vessel.rnWe must ensure the good state and/or the correct operation ofrnthe significant stations for safety which are the control of thernreactivity, the movement of control rods, the primary sodiumrncontainment and the decay heat removal.rnFor that, we monitor the main vessel, the conical skirt, thernIHX and the Core Cover Plug.rnA profound knowledge of the thermal transients of the past isrnnecessary to carry out an effective assessment.rnIn order to guarantee that any harmful situation is well takenrninto the management of aging, we monitor permanentlyrncertain measurements (primary and secondary pump speed,rnhot and cold pool temperatures, IHX-main vessel and reactorrnroof temperatures).rnWe present in the article the scientific method used in thernPhysics Section.rnA logical diagram specific to the type of situation and the structure allows to associate the harmful transient at a identical situation which has been happened in the past. During the last two cycles, the nuclear power plant has sustained 34 startup (20 during the 51st cycle and 14 during the 52nd cycle).rnAfter two cycles of operation, there is approximately 70 to 80% of occurrences authorized for the whole of the structures. For the last 4 cycles, the number of transients to come will remain quite lower than the number dimensioned initially.