Was polymer a codename?

James Mahaffey, in Atomic Accidents: A History of Nuclear Meltdowns and Disasters from the Ozark Mountains to Fukushima, one of his evocative trio of books published from 2009 to 2017, covers the 1952 Canadian NRX nuclear reactor accident. In a footnote, he raises a question (p. 151):

…the superintendent said “Dump the polymer!” I would have thought it correct to say “dump the deuterium oxide” or perhaps “dump the heavy water,” or even “dump the moderator,” but “dump the polymer”? Was “polymer” a code word for still-secret heavy water?

If you are completely mystified at this point, read no further. But if you are even vaguely aware of Canada’s heavy water reactor design, this might intrigue. In other words, for some time, was “heavy water” referred to as “polymer”? My own hazy understanding is that yes, WWII secrecy stipulated such a smokescreen, but for the life of me, I can’t recollect where I read this. And if you look at the Wikipedia entry for polymer and Google to get this paper called Deuteration and Polymers: Rich History with Great Potential, you’ll see there is a connection between deuterium (heavy water) and the large molecules known as polymers.

I remain uncertain on this point. And because I don’t want to go to that level of detail in my book, I guess I’ll never know.