Radiation Monitoring In Antarctica

Press, Volume CII, Issue 30062, 21 February 1963, Page 23

Radiation Monitoring In Antarctica

Background radiation in the McMurdo station area is very low, and there are no signs of any escape from the nuclear power reactor there, Mr D. E. Bernhardt, of the special projects branch of the Radiological Health Division of the United States Public Health Service, said in Christchurch. Mr Bernhard has just returned from four months at the base, where he monitored radio-activity in algae, water, air, and enow, from the base itself and to a lesser extent from other stations.

The public health service is under contract to the United States Navy to carry out “off-site” monitoring for any radio-active materials which may have escaped from the reactor, and for any environmental radiation. The Navy and the civilian contractors both do on-aite monitoring in the immediate neighbourhood of the reactor, which is on Observation Hill overlooking the station. The likelihood of any significant escape from, the reactor is very small indeed, as it is one of the most completely contained reactors in the world. Even in the “maximum accident,” as Mr Bernhardt put it, the radioactive products would be contained and could leak only gradually to the atmosphere, so that the bulk of the dangerous material would be diluted and to some degree have decayed before it reached the outside. These unusually strict precautions are necessary not only to protect the personnel, who might otherwise conceivably be marooned at

the base all winter exposed to dangerous amounts of radiation, but, in addition, to conform with the Anteratic Treaty, which requires that there must be no disposal of

radio-active waste on the continent, whether intention®! or otherwise. Also to conform to this requirement, spent products from the reactor have to be Shipped out of Antarctica. The rate of fall-out at McMurdo was considerably tower than in the United States, Mr Bernhardt said, and he had the impression that it was rather lower than in New Zealand. This was to be expected on general principles, since the, maximum rate of fall-out in either hemisphere tended to occur in middle latitudes, and debris tended to remain in the hemisphere in which it was created.

The level of radon and thoron gas in the atmosphere at McMurdo Sound was lower by as much as two orders of magnitude than in lower latitudes, Mir Bernhardt added. This was possibly because the gases were trapped by the permafrost (permanently-frozen subsoil) beneath the base. He had also taken samples at other places where there was a snow cover as well as the permafrost, and there the amounts of radon and thoron in the air were even lower. The gases were derived ultimately from uranium and thorium in the underlying rocks.

A particular isotope for which a search is being made in the atmosphere at McMurdo Sound is argon--41, created by the irradiation of the normal argon-40 in the air immediately adjacent to the reactor. The search has not progressed far, but it seems from preliminary work that the concentration

of the isotope is probably below the minimum sensitivity of the instruments.

Another United States installation which Mir Bernhardt was responsible for monitoring was the Snap 7C automatic weather-station, 60 miles from McMurdo station. The station is powered by the decay of stron-tiuzn-90, and Mr Bernhardt had to cheek that there was no escape of the isotope from the strontium source.

Mr Bernhardt was unable to distinguish with any certainty between the various isotopes present in the fallout oyer McMurdo Sound, but a multichannel analyser to detect at least any isotope arriving in substantial quantities is soon to be installed by the Navy. Another piece of new equipment, for the detection of iodine-131, has been taken to McMurdo Sound by Mr Bernhardt’s successor, Mir R. Mikkelsen.