Plant MaterialsDOE-HDBK-1017/2-93EFFECT DUE TO NEUTRON CAPTURETABLE 2Effect of Fast-Neutron Irradiation on theMechanical Properties of MetalsIntegrated RadiationTensile YieldFast FluxTemperatureStrengthStrengthElongationMaterial(NVT)(C)(MPa)(MPa)(%)Austenitic SS0------ 57623565Type 3041.2 x 102110072066342Low Carbon0------ 51727625steel2.0 x 1019806766346A-212 (.2%C) 1.0 x 10208080075242.0 x 1019293 70352492.0 x 101940457929314Aluminum0------ 1246528.86061-01.0 x 10206625717722.4Aluminum0------ 31026517.56061-T61.0 x 10206634930616.2Zircaloy-20------ 276155131.0 x 10201383102794One of the areas of the reactor vessel that is of most concern is the beltline region. The NuclearRegulatory Commission requires that a reactor vessel material surveillance program beconducted (in accordance with ASTM standards) in water-cooled power reactors. Specimensof steel used in the pressure vessel must be placed inside the vessel located near the insidevessel wall in the beltline region, so that the neutron flux received by the specimensapproximates that received by the vessel inner surface, and the thermal environment is as closeas possible to that of the vessel inner surface. The specimens are withdrawn at prescribedintervals during the reactor lifetime and are subjected to impact tests to determine new NDTtemperatures. Figure 5 shows the increase in NDT temperature for a representative group of lowcarbon steel alloys irradiated at temperatures below 232C. Many current reactors have corepressure vessel wall temperatures in the range of 200C to 290C, so that an increase in NDTis of very real concern.Irradiation frequently decreases the density of a metal over a certain temperature range, so thata specimen exhibits an increase in volume or swelling. The swelling of stainless steel structuralcomponents and fuel rod cladding, resulting from fast neutron irradiation at the temperaturesexisting in fast reactors, is a matter of great concern in fast reactors. The swelling can causechanges in the dimensions of the coolant channels and also interfere with the free movement ofcontrol elements. Rev. 0Page 41MS-05
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business