b'Expansion of LWR Loop Testing InfrastructurePrincipal Investigator: Nate OldhamTeam Members/ Collaborators: Kendell Horman, Lex Strain, Kelly Ellis, Thomas Maddock, Justin Johnson,Bubba Ricker, and Josh TonksI-Loop design and safetyE xpand access and capabilityand other equipment. In order to to the Advanced Test Reactorprovide the neutronics to approximate evaluations have been(ATR) Medium-I position withprototypic LWR heating rates, nuclear performed and showa flowing water loop, allowing testinggrade Zr-2.5Nb will be used for the that the I-Loop designof fuels and materials in prototypicexperiment tubes. The improvements effort in ATR is a viablelight water reactor (LWR) conditions. will enable advanced fuel qualification strategy to address LWRProject Description: to continue at the Idaho National Labo-fuel irradiation testingThe closure of the Halden Boilingratory (INL) and support the industry capability gaps left byWater Reactor (HBWR) and growingand DOE desire for these capabilities the HBWR closure asdemand for extending LWR fuelin the United States, to support the well as enhance testingperformance limits, has createdcontinued safe use of existing LWR capabilities includingurgency to find a testing solution toreactors and provide for future fuel ramp testing support near-term fuel testing needs.testing for next generation reactors.This need comes at a time whenAccomplishments:industry, via Electric Power ResearchATRs original Top Head Closure Plate Institute (EPRI), and the Department of(Figure 1) was successfully replaced Energy (DOE), via the Accident Tolerantwith the Mark II (Figure 2) design in Fuels (ATF) Program, are pushing forJuly 2021 during the reactors Core performance and capability increasesInternal Changeout (CIC) outage. This for new fuels. The I-Loop project aimsis a critical accomplishment because a to fill the gap created by HBWRsCIC is the only time to perform such a closure and provide a similar capabilitylarge effort and because the next CIC at ATR, by installing a flowing wateroutage is estimated in the year 2038. loop in one Medium-I position andThe replacement of the Top Head providing access to the other Medium-IClosure Plate provided the opportu-positions for future experiments. Innity for the replacement of the o-ring order to provide better access to theseals which have been in-service since I-positions of ATR, a new Top Headthe first startup in 1967. The Mark II Closure Plate (Mark II) has beendesign possesses several new features installed, expanding the capabilities ofthat allow for testing and maintenance the ATR for continued fuel and mate- of the reactor to ensure ATR operates rials testing. To support the flowingsafely and reliable well into the future. water loop, the refurbishment of theThe main design feature of the Mark 1A cubicle will be required includingII is the additional eight I-penetrations new pumps, piping, heat exchangers,on the periphery of the nine in-pile 136 2021|AFC ACCOMPLISHMENTS'