No. It was a carbon-moderated light-water reactor or "light water graphite reactor" (LWGR), a very old reactor type with extremely dangerous characteristics. I think the Brits may have built some of these as power reactors VERY early on in the atomic age, but do not think the US ever did so.
If the temperature of the graphite gets too high, the water can react with the carbon and make carbon monoxide and hydrogen (called the "water gas reaction", and widely used in the late 1800's to produce "illuminating gas" from coal). That reaction can cause a large pressure surge inside the reactor, and if the vessel cracks and air gets inside......BOOM-ski!
Steam/gas bubbles—positive void coefficient?
Thanks for the information... Interesting.