Book Description

In late 2003 it became evident that U-Mo aluminum fuels under development exhibited significant fuel performance problems under the irradiation conditions required for conversion of most high-powered research reactors. Solutions to the fuel performance issue have been proposed and show promise in early testing. Based on these results, a Reduced Enrichment Research and Test Reactor (RERTR) program strategy has been mapped to allow generic fuel qualification to occur prior to the end of FY10 and reactor conversion to occur prior to the end of FY14. This strategy utilizes a diversity of technologies, test conditions, and test types. Scoping studies using miniature fuel plates will be completed in the time frame of 2006-2008. Irradiation of larger specimens will occur in the Advanced Test Reactor (ATR) in the United States, the Belgian Reactor-2 (BR2) reactor in Belgium, and in the OSIRIS reactor in France in 2006-2009. These scoping irradiation tests provide a large amount of data on the performance of advanced fuel types under irradiation and allow the down selection of technology for larger scale testing during the final stages of fuel qualification. In conjunction with irradiation testing, fabrication processes must be developed and made available to commercial fabricators. The commercial fabrication infrastructure must also be upgraded to ensure a reliable low enriched uranium (LEU) fuel supply. Final qualification of fuels will occur in two phases. Phase I will obtain generic approval for use of dispersion fuels with density less than 8.5 g-U/cm3. In order to obtain this approval, a larger scale demonstration of fuel performance and fabrication technology will be necessary. Several Materials Test Reactor (MTR) plate-type fuel assemblies will be irradiated in both the High Flux Reactor (HFR) and the ATR (other options include the BR2 and Russian Research Reactor, Dmitrovgrad, Russia [MIR] reactors) in 2008-2009. Following postirradiation examination, a report detailing very-high density fuel behavior will be submitted to the U.S. Nuclear Regulatory Commission (NRC). Assuming acceptable fuel behavior, it is anticipated that NRC will issue a Safety Evaluation Report granting generic approval of the developed fuels based on the qualification report. It is anticipated that Phase I of fuel qualification will be completed prior to the end of FY10. Phase II of the fuel qualification requires development of fuels with density greater than 8.5 g-U/cm3. This fuel is required to convert the remaining few reactors that have been identified for conversion. The second phase of the fuel qualification effort includes both dispersion fuels with fuel particle volume loading on the order of 65 percent, and monolithic fuels. Phase II presents a larger set of technical unknowns and schedule uncertainties than phase I. The final step in the fuel qualification process involves insertion of lead test elements into the converting reactors. Each reactor that plans to convert using the developed high-density fuels will develop a reactor specific conversion plan based upon the reactor safety basis and operating requirements. For some reactors (FRM-II, High-Flux Isotope Reactor [HFIR], and RHF) conversion will be a one-step process. In addition to the U.S. fuel development effort, a Russian fuel development strategy has been developed. Contracts with Russian Federation institutes in support of fuel development for Russian are in place.