Review of small specimen test techniques for irradiation testing
- PDF / 1,716,629 Bytes
- 15 Pages / 594 x 774 pts Page_size
- 28 Downloads / 248 Views
I.
INTRODUCTION
THE evolution of nuclear power reactors has always faced limitations imposed by the behavior of materials used to form the structure in or around the active nuclear process zone, be it fission or fusion. Early piles and research reactors had to be built with little or no information on the effects of neutron irradiation on materials.I~'2'31 However, initial experience with metallic uranium fuel demonstrated dramatic effects of irradiation on the dimensional stability and mechanical properties of these materials, t2] and experiments were quickly inserted into reactors to investigate the effects of neutron irradiation on other structural materials. [4j For instance, the effects of neutron irradiation on stainless steels and magnesium and zirconium alloys used in both production reactors and early power reactors were examined by postirradiation testing of core components, as well as a variety of specimen types inserted into test reactors ranging from tensile specimens to creep and stress relaxation specimens. [2,3,5] While some of these were standard or near-standard in geometry and size, a number of specimen geometries were novel or scaled versions of standard specimens. Hence, early on, irradiation testing of materials became an important component of nuclear systems development, and it is an integral part of current programs to develop improved materials for both light water and fast reactor structures. These programs involve the in-reactor testing of specimens as well as the extraction and testing of specimens from irradiated components. In both instances, reduction in specimen size has been necessitated by restrictions in irradiation vol-
G.E. LUCAS, Professor of Nuclear Engineering and Materials, is with the Departments of Chemical and Nuclear Engineering and Materials, respectively, University of California, Santa Barbara, Santa Barbara, CA 93106. This paper is based on a presentation made in the symposium "Irradiation-Enhanced Materials Science and Engineering" presented as part of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25-29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD. METALLURGICAL TRANSACTIONS A
ume or limitations in the amount of material available from irradiated components. Specimen size has also been limited in surveillance programs. Concern over irradiation effects on pressure vessels, which were not to be removed periodically like fuel assemblies, led to the insertion of surveillance packages near the reactor core to provide early indications of property degradation. These packages largely contained Charpy V-notch (CVN) specimens. Historically, these have been used to monitor irradiation-induced changes in the temperature delineating ductile and brittle fracture regimes. Such changes are then indexed to changes in the temperature dependence of fracture toughness, t6] a property which requires much larger specimens to determine directly. However, more recently, there h
Data Loading...
