Management of Radioactive Wastes
C. A. MAWSON, Head
Environmental Research Branch
Chalk River Nuclear Laboratories
Atomic Energy of Canada Limited
Chalk River, Ontario
INTRODUCTION
When I first became concerned with radioactive waste management, in the
early 1950's, very little was really known about the subject. There was a general
feeling that it was a serious "problem. " Articles were appearing in the press and
talks were being given on the radio suggesting that the wastes generated by the
proposed nuclear power reactors might he a serious menace to humanity. The
prophets pointed with alarm to the enormous quantities of fission products that
would accumulate steadily over the years in tank farms associated with reactor
fuel reprocessing plants, and calculations were made of the possible results from
rupture of the tanks due to corrosion, earthquakes or enemy attack. Responsible
people suggested seriously that the waste disposal problem might be fatal to the
development of a nuclear power industry, and this attitude was reinforced by the
popular outcry that arose from experience with fallout from nuclear weapons testing.
The Canadian nuclear power industry was not critically involved in this controversy because our heavy-water reactors are fuelled with natural uranium, and
reprocessing of the fuel is not necessary. The spent fuel contains plutonium, a
potential fuel, but the cost of recovering it was such that it was not competitive
with natural uranium, which is not in short supply in Canada. Our spent fuel is
not dissolved in acid - it is stored, still in its zirconium cladding, under water at
the reactor site, or placed in sealed concrete-and-steel pipes below ground. If
the price of uranium rises sufficiently it will become profitable to recover the
plutonium, and only then shall we have an appreciable amount of waste from this
source.
However, during the first five or six years of research and development at
Chalk River we did investigate fuel processing methods, and like everybody else
we hsd stainless steel tanks containing high and medium level wastes. These
were located quite close to the Ottawa River, and we worried about what would
happen if they leaked. We did not know to what extent the fission products, such
as strontium-90, cesium-137 and cerium-144, would be held back by adsorption
onto the soil, nor did we know the dilution regime of the river.
NEPHELINE SYENITE GLASS FIXATION
Before it was finally decided not to reprocess power reactor fuel we started
development of a method for fixation of wastes into glass. By the time this technique had successfully passed its pilot-plant stage that decision was taken, and a
commercial-scale plant was never built, but a brief description of the process
may be of interest.
Our high-level reprocessing wastes were in solution in concentrated nitric
acid. Watson and his co-workers (1) found that if the acid solution was poured
onto  powdered nepheline syenite a gel was formed which absorbed the liquid.
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