Aqueous Homogeneous Research Reactors

Let me tell you about Aqueous Homogeneous Research Reactors. These were reactors with fluid fuel: an aqueous solution of uranium. Aka "water-boiler" type reactors. The first few were made at LANL during the Manhattan Project. Later, Atomics International sold them for research.

These reactors were nice for research because they were small, inherently safe due to strong negative reactivity feedbacks, "easy" to maintain, and could be operated with a small crew. Here's one being built at the Armour Research Foundation in Chicago (now @IITRI_Chicago)

Research reactors of this type were installed by Atomics International around the world, including in Laramie, Berlin, Tokai, Risø, Frankfurt, Geneva, Mayaguez, and Milan

Because the fissions are happening amongst the water, radiolytic decomposition of water happened constantly. 10 liters of hydrogen and oxygen gases are released per minute when operating at 50 kW. Gas recombiners were developed to deal with this.

The recombiner offered a somewhat unique experimental capability, where the decaying fission gases would release strong gammas far away from the neutrons. Having pure-gamma facilities was useful for much research.

Here's a typical control console for one of these

Atomics International basically serialized production of these AHRs. They had an assembly line for them.

REACTORS READY FOR CRATING. Easily installed in any standard laboratory!

Overall, a cool part of reactor history. I bought this pamphlet on ebay, and it came in the mail yesterday. I scanned it last night at 600 dpi and have posted it at Aqueous Homogeneous Research Reactors (brochure). Lots more cool stuff in there.

Oh neat: the Laramie one was a L-77 at University of Wyoming, as recently discussed in this great article Lost in Time: There was a Working Nuclear Reactor at UW 60 Years ago