Press coverage of the Society and its activities

Detection of airborne radioactivity

Written by
Jim Ungrin
the North Renfrew Times
2021 Oct 06

Ottawa-built, Type 6, Hughes-Owens radium-illuminated aircraft compass.

This is another in the series of anecdotes taken verbatim from Les Cook’s unpublished book “Birthpangs of CANDU”, a copy of which is in the documents held by the Society for the Preservation of Canada’s Nuclear Heritage Inc. (Les Cook was the Director of the Chemistry and Metallurgy Division of CRNL from 1945 to 1956.) The anecdote reports another hazard associated with the radium industry discussed in two previous Nuclear Heritage columns:

“Soon after the first Russian bomb tests began, we were offered pieces of filters that had been flown through radioactive dust clouds as they passed over Japan. We became immediately aware of the need to set up a “lowest possible background” laboratory so we could extract a maximum of information from such windfalls (and, as we soon found out, local rainfalls as well).

Accordingly, we set up a small building in the town of Deep River well away from any possible background contamination from the plant 5 miles away. Bill Grummitt was installed there to become our super-low-level specialist.

Bill developed two basic techniques. One was to isolate radioactive particles from the filters by exposing photographic film to the filter, cutting out particles showing spots of radioactivity, dispersing the patch and repeating the procedure. It was a thrill of sorts to isolate small particles, easily visible under a microscope, that had come all the way from the Russian test site, reported to be in the Gobi desert.

More productive, however, was Grummitt’s analysis of the radioactivity in such particles. We developed and used both alpha and beta counters with extremely low background levels – alpha chambers with perhaps only one background alpha count every hour or so, and beta counters with the count at less than one per minute. These backgrounds were ten to one hundred times lower than anything we normally needed or used.

With these levels one could indeed discover whether a given sample of dust came from a U235 explosion or a plutonium one. Also, we could make a rough shot at the efficiency of the explosion. Soon we discovered that the radioactive clouds both from the Gobi and from the US testing grounds often came right over Deep River, and if we were fortunate and it rained at the time, we could collect all the sample we needed in a few gallons of rain water.

This work soon got to be routine and a bit boring, and we decided to try to work it off on the Defence Research Board laboratories in Ottawa. We helped them set up a sampling station on top of a building near the National Research Council on Sussex Street and with some analytic equipment. They had hardly got going when we had an urgent phone call from them. There was radioactivity in the rain, long-lived. We were frankly puzzled. As far as we knew, there had been no bombs lately. It sounded as though it was probably radium, but where could radium, floating over the city of Ottawa, come from?

Our DRB associate sent a gallon of rain up to Bill Grummitt, who soon confirmed it contained radium. That posed our friend a real challenge. He solved it by examining wind direction reports and concluded that the source was somewhere right in downtown Ottawa. How he zeroed in on Hughes-Owens instrument store I never knew. Apparently, the company used radium luminous paint and burned their waste rags in their basement furnace and, sure enough, they were burning them on that very day. They never imagined they would get caught, or indeed that it mattered at all. They were certainly surprised, and immediately discontinued this method of disposal.

The Society would be very pleased to receive further anecdotes about the early days of the nuclear industry. Anecdotes can be sent to