en.wikipedia.org/wiki/Project_Pluto

Official Tory II-C design documentation describes the reactor's control system as hafnium control rods inserted axially into the core. One Lawrence Radiation Laboratory report on Tory II-C control states: "Neutronic control of Tory II-C is to be achieved by 12 hafnium control rods..." Another Tory II-C structural design report lists the reactor component materials and identifies "Control Rods — Hafnium."

So this infobox entry is not describing Tory II-C correctly. May 1964 Pluto documentation distinguishes Tory II-C's hafnium control rods from other control concepts; "boron control drums" does not match the cited Tory II-C design sources.

The Lawrence Radiation Laboratory report TORY IIC TEST OPERATIONS separates Tory II-C's first critical operation from its later full-power run. It has a section titled "Cold Critical Experiment (March 24, 1964)" and explains that the plan for that test was to bring the reactor critical at low power. The same report's introduction then says the program led to successful testing of Tory II-C at design conditions on May 20, 1964.

That means March 24, 1964 was the criticality date discussed in the test-operations report, while May 20, 1964 was the later design/full-power demonstration run. Labeling May 20 as the reactor's "Criticality (date)" conflates those two events.

Project Pluto fuel-fabrication reports describe this step differently from the article. In Technology of Ceramic Components: Part 3 of the Tory II-C Program, the process is described as follows: the nitrate solutions were slurried with BeO powder, and "the fuel is coprecipitated by the addition of ammonium hydroxide." A later Lawrence Radiation Laboratory fabrication report likewise lists ammonium hydroxide solution among the process materials used.

This matters chemically as well: ammonium hydroxide/ammonia is the precipitating base; ammonium nitrate is a nitrate salt and is not the reagent the cited fabrication reports say was added at this step. So the article's wording here appears to be a transcription/chemical error.