b'Status of ATF-2Principal Investigator: David KamermanTeam Members/ Collaborators: Gary Hoggard, Brian Durtschi, Bryon Curnutt and Stacey WilsonIrradiation of prototypic rodlets at conditions that are representative of commercial reactor environments is critical to the development of fuel performance data that can be used to develop licensing topical reports.T he ATF-2 experiment is part ofpellets. Irradiation began in June of the Development and Quali- 2018. The first three cycles (164A, fication phase of the Accident164B, and 166A) ran at lower linear Tolerant Fuel (ATF) program. Testheat generation (LHGRs) (180-240 rodlets of mature ATF technologies areW/cm). Subsequent cycles have been irradiated in a prototypic pressurizedrunning at high power (350-400 W/water loop in the center flux trap ofcm). The first two cycles (164A and Advanced Test Reactor (ATR) at Idaho164B) ran with lower flow rates of National Laboratory (INL). approximately 35gpm and cooler Project Description: inlet temperatures of approximately The ATF-2 experiment consists250C. Subsequent cycles ran with of 6 tiers of test rod holders eachhigher flow rates of approximately containing a 2x3 grid of 15 cm test50gpm and inlet temperatures of rodlets. A graphical rendering of theapproximately 280C. Loop thermal test train is shown in Figure 1. Each ofhydraulic data is available for each the test rodlets contain 10 pellets ofcycle. An example, cycle 168A, which fuel each of which is approximatelyhad numerous mid-cycle shutdowns is 1cm long. Tiers 5 and 6 are combinedshown below in Figure 2.into a single tier of longer test rodsAccomplishments:at the top of the test train. The testForty-one rodlets have been irradiated rodlets are supplied by each of theto date and the highest burnup rod three vendor teams and consist ofis projected to reach over 30 GWd/their leading and most mature ATFMTU by the end of cycle (EOC)169A concepts. Concepts irradiated to dateprior to ATRs core internal changeout include coated cladding, iron chrome(CIC). Power histories are evaluated aluminum cladding, and doped fuelat the end of each cycle following 84 2020|AFC ACCOMPLISHMENTS'