Use of Axially zoned gadolinia in GE [General Electric Co.] BWR reload fuel

General Electric Company (GE) has used gadolinia as a burnable poison in boiling water reactors (BWRs) since its commercial introduction in 1971. With the introduction of GE's GE8B reload product line, axial gadolinia zoning has been utilized to provide multiple design benefits. The first full reload batch of GE8B fuel began operation in early 1987. As of mid-1988, GE8B reloads have been operated in ten BWRs. These reloads have spanned the range of GE plants from BWR/3 through BWR/6. Of these ten applications, five have been designed for increased burnup, four for longer cycles (up to 2 yr), and three for power uprates of ∼4%. Some plants were able to obtain multiple benefits, such as increased cycle energy and power uprate, or higher burnup and increased energy. Fourteen different GE8B bundle designs were used for these applications, since many applications utilize two-stream loading for additional flexibility. The PSZ was used in 50% of these bundles, the SDZ was used in 64%, both were used in 43%, and neither in 29%. These statistics indicate the broad range of applications provided by the axial gadolinia zoning options available with GE8B. The flexibility to design with any combination of these options, as dictated by the particular application, has helped to make custom bundle design a reality