American nuclear had a loud summer. Two reactors went critical in Idaho in June alone, and the same patch of desert has more waiting their turn.<\/p>\n
None of that fuel gets approved because a company says it works. Somebody has to pull a used rod out of a reactor, cut it open and measure what the neutrons did to it, and in this country that work lands almost entirely in one building. It sits behind four feet of concrete, and the room where the fuel goes has argon in it instead of air.<\/p>\n
The building is the Hot Fuel Examination Facility at Idaho National Laboratory, it opened in 1975, and in August it picked up a plaque from the American Nuclear Society naming it a Nuclear Historic Landmark. A plaque like that usually goes to a place that has finished its career.<\/p>\n
This one is booked solid.<\/p>\n
A hot cell is a sealed room you operate from the outside. Nobody walks in. Operators stand at a window, push their hands into mechanical arms that reach through the wall, and do the work by remote control on the far side of the glass. At HFEF the glass is leaded, the walls are four feet of concrete, and 15 workstations run along the main cell.<\/p>\n
That main cell measures 70 feet long, 30 feet wide and 25 feet high (21 by 9 by 7.6 meters), which per Idaho National Laboratory<\/a> makes it the largest inert atmosphere hot cell in the United States for nuclear materials research. Its steel liner is metallized with zinc. Next door sits a smaller air-filled cell for decontaminating and disposing of whatever comes back out.<\/p>\n Argon fills the big one. Argon barely reacts with anything, so metallic fuel, sodium residue and freshly cut cladding can sit exposed in there without oxidizing or catching fire. The concrete handles the other problem, which is you. Fuel that has been in a reactor core throws gamma radiation, and four feet of concrete plus leaded glass is what stands between that and the person working the manipulators.<\/p>\n Underneath the main cell there is a reactor. The Neutron Radiography Reactor, NRAD for short, is a 250-kilowatt open pool TRIGA that has been running since 1977, and it is the 52nd reactor built in Idaho. It exists to take pictures.<\/p>\n Neutrons and X-rays see pretty much opposite things. An X-ray gets stopped by dense metal and sails through light elements, while a neutron beam goes through the metal and gets caught by hydrogen and other light atoms. Aim that at a used fuel rod and you get an image of the inside of the cladding without cutting anything.<\/p>\n NRAD hit its 5,000th reactor run on February 18, 2026, testing a new high-resolution digital neutron imaging system. It also does work nobody would call photography. Scientists used NRAD’s north radiography station for the zero-power criticality test of Unity, the 1-megawatt microreactor that went critical on June 30<\/a> and became Idaho’s 54th reactor. Number 53, the Antares Mark-0<\/a>, got there on June 4.<\/p>\n The country does not have much shielded cell space, and the quickest way to get more is to empty out what already exists. In summer 2024, engineers at the Materials and Fuels Complex started clearing the space behind HFEF’s 9M window: jack plates, support assemblies, material baskets, heater units and a great deal of wire and cable. More than 10,000 pounds of it came out, and every piece had to be decontaminated before anyone could dispose of it.<\/p>\n So what is the cleared space for?<\/p>\n Sodium test loop work at TREAT, the transient test reactor at the same complex. A sodium loop is a sealed cartridge that holds a fuel specimen in liquid sodium, so researchers can hit it with a burst of power and watch a sodium-cooled fast reactor accident happen with instruments running. Loading pre-irradiated fuel into that cartridge takes a big cell with remote handling, which is the piece HFEF supplies.<\/p>\n Idaho has run this play before. In the 1970s and 1980s, fuel irradiated in EBR-II went to TREAT for sodium loop experiments and came back to HFEF for examination afterward. The lab has not said when the first of the new loops goes in.<\/p>\n Doug Crawford, chief reactors technologist at the Materials and Fuels Complex, told INL that the facility’s workload in its second half-century is as heavy as it has ever been, and that “HFEF’s flexibility and continued adaptation to changing needs over 50 years is remarkable.”<\/p>\n Fuel rods arrive by truck. A cask comes into the HFEF bay, cranes lift the lid, and the rods go into the cell. One shipment from a commercial plant brought 25 rods, each 12 feet long, carrying about 100 pounds of heavy metal between them, mostly uranium. INL says a second delivery of next-generation fuel irradiated in a US power reactor arrived in December.<\/p>\n The tooling in there is frankly less futuristic than you would expect. Operators mark the cut locations with a Sharpie wrapped in tape, because the tape gives the manipulator claws something to grip. A pipe cutter of the sort a plumber owns makes the rough cut, and a diamond saw makes the fine one. A laser punctures the cladding so the fission gas that built up inside can be captured and measured. Fabiola Cappia, who directs fuels post-irradiation examinations at INL, leads that side of the work.<\/p>\n Private companies are lining up for the same equipment. The uranium-zirconium samples we followed into the Advanced Test Reactor<\/a> came out of the core on May 6 and are cooling ahead of their own teardown.<\/p>\n The heaviest job on the schedule has been sitting on a concrete pad in Virginia since 2017. Thirty-two high-burnup fuel assemblies went into an instrumented dry storage cask at the North Anna plant, wired with temperature probes, and stayed there to age under real storage conditions. Idaho and the Department of Energy signed a targeted waiver on April 29, 2025 that lets the cask travel, and INL expects it around 2027. Opening it and taking fuel out of it needs a hot cell that can swallow the cask whole.<\/p>\n Handing a landmark plaque to a building with a waiting list is a slightly odd thing to do, and I suspect the crews there will take it anyway. ANS president Mark Peters unveiled HFEF’s plaque outside the facility on August 12, alongside INL director John Wagner<\/a> and the staff who run the place. It is INL’s 10th entry on a list of 101 sites the society has kept since 1985.<\/p>\n Image credit: ORNL<\/em><\/strong><\/p>\n","protected":false},"excerpt":{"rendered":" American nuclear had a loud summer. Two reactors went critical in Idaho in June alone, and the same patch of … <\/p>\nThe reactor lives downstairs<\/h2>\n
Ten thousand pounds behind window 9M<\/h2>\n
HFEF is busier now than it was in 1975<\/h2>\n
A cask from Virginia is due in 2027<\/h2>\n