Paul Wilson

UWNR is a 1 megawatt (MW) TRIGA pool reactor (see Chapter 1) housed on the University of Wisconsin campus in Madison, Wisconsin. Its primary mission is the training of undergraduate and graduate nuclear engineering students; however, it is also used to perform research, including irradiation for neutron activation analysis.

The reactor first went critical as a 10 kilowatt (kW) LEU-fueled reac­tor in 1961 and, following several power upgrades, was converted to HEU fuel in 1979. It was converted back to LEU fuel 30 years later, successfully achieving criticality in 2009. At that time, UWNR was converted from us­ing 70 percent enriched TRIGA-FLIP (Fuel Life Improvement Program) fuel to TRIGA LEU 30/20 (30 percent uranium by weight, 20 percent enriched) fuel. The new LEU fuel is, like the previous FLIP fuel, a standard TRIGA — type fuel element containing erbium-doped uranium-zirconium hydride (UZrHx-Er) fuel (see Chapter 2).