Thirty years of fuels and materials information from EBR-II

Abstract

The Experimental Breeder Reactor-II (EBR-II) was a 62.5 MWt±20 MWe sodium cooled fast reactor that was operated successfully for 30 years. Over its period of operation a wealth of fuels and materials information originated from EBR-II. Several missions were conducted in EBR-II, all of which yielded new and valuable additions to the world's knowledge base for nuclear materials. Some of the ®rst pioneering experiments on irradiation eects in stainless steels were conducted in EBR-II. Later, practical manifestations of enhanced irradiation creep, swelling, and loss of ductility were experienced on EBR-II components. In addition, for a period of more than 15 years, the EBR-II reactor would become the primary irradiation facility for all fast reactor fuels and materials research and development. Both the initial mission and ®nal mission for EBR-II (the Integral Fast Reactor Concept, IFR), involved the remote reprocessing and irradiation of fast reactor metallic fuels. The fuels and materials information gleaned from these missions will be summarized with the intent of portraying a sample of the valuable legacy that EBR-II contributed to the world's store of nuclear fuels and materials knowledge.

In-Vessel Coil Material Failure Rate Estimates for ITER Design Use

“…The reactor used seven cores from 1965 to 1969 (Stevenson 1987) and typically one core per year after 1969. The technology for fabricating the fuel assemblies in the hot cell matured, and after completing tests to high fuel burnup (greater than 10 atom%) to intentionally fail cladding (Seidel and Einziger 1977), the plant operated with less than one tube breach failure per core (Walters 1999). The breaches experienced in operations were typically intergranular cracks, often at the restrainer "dimples."…”

“…The breaches experienced in operations were typically intergranular cracks, often at the restrainer "dimples." These dimples were indentations to prevent the metallic fuel bar inside the cladding tube from ratcheting upward in the tube then dropping back down to the bottom of the tube-thereby creating a neutron reactivity insertion event in the core during reactor operation (Walters 1999). The failure mode of these tubes was predominantly breach by cracking.…”

“…The IVC stainless steel pipe sees vacuum on the exterior and solid magnesium oxide insulation on the interior as a static configuration. The EBR-II cladding had very low, or even non-existent, flow corrosion issues (Walters 1999). Therefore, no correction to the EBR-II data is needed to apply it to the IVC.…”

“…Initially the staff continued to use SS 304L in Mark-II fuel, but then SS 316 was also used in Mark-II, Mark-IIC, and Mark-IICS fuel (Lahm et al 1993). 30,000 Mark-II cladding tubes were used with excellent results (that is, high reliability of less than one tube failure per core) when uranium burnup was held to 8 atom% (Walters 1999). From that experience, we can conclude that the dimples in the tube walls did not always cause a stress riser for crack growth.…”

“…From that experience, we can conclude that the dimples in the tube walls did not always cause a stress riser for crack growth. Given the discussions by Walters (1999) and Lahm et al (1993), it is reasonable to assume that the cladding performance was good across each of the cladding materials. Therefore, the basic "per core" failure rate of the cladding given above should apply to any of the austenitic stainless steel cladding materials-304, 316, cold worked 316, and cold worked D9, as well as the ferritic steel HT-9.…”