Low Enriched U-10Mo Fuel Plate Characterization and Review of De-Cladding for Research Reactor Applications

摘要

The National Nuclear Security Administration (NNSA) Office of Material Management and Minimization (M~3) United States High Performance Research Reactor (USHPRR) project is developing a low enriched uranium-molybdenum (U-Mo) fuel as a candidate replacement for the highly enriched uranium (HEU) fuels currently being used in the U.S. high performance reactors. The USHPRRs include the Massachusetts Institute of Technology Reactor (MITR), University of Missouri Research Reactor (MURR), National Bureau of Standards Reactor (NBSR) at the National Institute of Standards and Technology, Advanced Test Reactor (ATR) at the Idaho National Laboratory, and High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. The proposed baseline fuel for MITR, MURR, NBSR, and ATR utilizes an aluminum cladding similar to the present generation of fuel; however, the fissionable component of the fuel consists of a low enriched uranium with 10% molybdenum (U-lOMo) monolithic alloy with a thin layer of zirconium separating the fuel core from the cladding. The M~3 Convert team is working with the national laboratory complex to develop and qualify the low enriched uranium (LEU) fuel and facilitate the research reactor conversions starting with the Nuclear Regulatory Commission licensed HPRRs, (i.e., MIT, MURR and NBSR reactors). The new LEU fuel consists of plates with a monolithic U-lOMo center layered on both sides with co-rolled zirconium and then entirely clad in aluminum 6061. The new LEU fuel design allows for greater uranium density than in the HEU dispersion fuels. Fresh fuel fabrication scrap materials are generated throughout the USHPRR fuel fabrication process. Options for recovery of the LEU metal from this scrap with the purpose of reusing the LEU material in a future LEU casting are being evaluated. One step in the recovery of this LEU metal is to remove the aluminum cladding from the fuel plates. The evaluation of the overall effectiveness of the dissolution process to remove the aluminum cladding, including a metallurgical analysis of the mini plates before and after the decladding process, is discussed in this paper.