REVIEW OF RADIATION INDUCED DEGRADATION OF CONCRETE STRUCTURE IN COMMERCIAL NUCLEAR POWER PLANTS AROUND REACTOR VESSEL

摘要

Most U.S. reactors have been granted a renewal oflicense to extend their operation from 40 to 60 years. TheU.S. Nuclear Regulatory Commission has begun thesubsequent license renewal process, reviewing licenseapplications that would extend those reactors’ operatinglifetimes by an additional 20 years (80 years total) ifapproved.Reactor operation beyond 60 years (long-termoperation) is expected to accumulate neutron fluence andgamma dose to levels that can potentially cause somedegradation of the concrete bioshield and reactorpressure vessel (RPV) support structures. Past researchindicates that the radiation degrades the concrete’sphysical and mechanical properties. Further research isongoing to evaluate the safety performance of the RPVsupport structures.This paper summarizes our efforts in reviewing theavailable data pertaining to 1) RPV support designs,2) anticipated radiation fluence/dose levels in the reactorcavity, and 3) the degradation effects of neutron andgamma radiation on concrete structures under conditionsfound in light water reactor cavities.There is a potential for all operating pressurizedwater reactors to exceed a neutron fluence level that iscommonly accepted to indicate the onset of concretedegradation. Most boiling water reactors are notexpected to reach that level, though each plant should beevaluated using plant-specific conditions.