Cold-War Era Nuclear Research

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The chemists at Shirleys Bay were joined by physicists in 1952, when DRCL began participating in nuclear defence research. In April of that year, the USSR shocked many of the other powers by exploding a thermonuclear device, thereby demonstrat­ing their growing nuclear capabilities. The Cold War was in full swing, and this event had an immediate effect on the research conducted at DRCL.

DRB decided to allocate a significant amount of effort to nuclear-defence research and suggested that as much as 50% of the efforts of the Suffield Experimental Station and DRCL be diverted in that direction.

In October 1952, Canadian scientists participated in the first UK nuclear-weapons trial, Operation Hurricane, off the coast of Australia. Canadians were there assist­ing the British Atomic Weapons Research Establishment (AWRE). After the war, Britain had experienced a shortage of trained scientists of the AWRE, and, given that Canadian scientists were closely involved in the research on nuclear energy during the war, the Chairman of DRB, Dr. Solandt, had offered the services of the Canadian scientists for AWRE activities.

Dr. J. A. Carruthers was one of the Canadian scientists seconded to AWRE and was responsible for measuring the thermal effects of the nuclear weapon at Operation Hurricane. He returned to Canada in 1953 and set up a Radiation Physics Group at DRCL.

At this time there was an acknowledged need for the Allied countries to coordi­nate their research on nuclear warfare. This was achieved through the formation of cooperative international research programs, ultimately evolving into The Technical Cooperation Program (TTCP), with the US, Canada, the UK, and Australia as participants.

The three original participants of this cooperative body (the US, Canada, and the UK) discussed how the research would be best undertaken, and decided that Canada’s DRCL would provide research in five areas: thermal effects of nuclear weapons; radiac instrumentation; physics of ionizing radiation; chemical effects of ionizing radiation; and biological effects of ionizing radiation.

Thermal Effects of Nuclear Weapons

Canadian scientists again took part in British atomic-weapons trials in Australia in 1956-57. Teams from the Suffield Experimental Station (later DRES) took shock-wave measurements using the smoke-rocket technique, and attempted to measure flux and spectrum of neutrons from the weapons via their associated beta rays. A team from DRCL, led by Carruthers, took thermal measurements, including all radiations in the UV, visible, and infrared regions.

In the fall of 1956, DRCL sent a team to make observations at Operation Buffalo, a series of four nuclear blast tests conducted by the British at Maralinga in South Australia. Operation Buffalo was the first series of tests here, and living quarters and experimental facilities were still being completed when the scientific teams arrived and began their work. A British historian has described the type of studies undertaken at Operation Buffalo: “The [British] military built a large village of prefabricated huts, and an army of dummy men and live domestic and farm animals were placed close to ground zero and exposed to the blast. Some 250 servicemen from Commonwealth countries, named the Indoctrinee Force, observed the surface blast from a distance of four and a half miles and then made a two hour inspection of the aftermath, wearing protective clothing and respirators.”

From the point of view of the Canadian researchers, Operation Buffalo was a success. Parr Tate recalled:

“While conditions were uncomfortable and difficult, virtually all experiments which had been planned by the DRCL thermal-measurements team were made successfully. Observations were made on the shape of the thermal pulse by Dr. Carruthers and Doug Pattman with special high-speed bolometers developed by them. The thermal pulse was also recorded at lower time-resolution by radiometers, and the total heat flux by calorimeters. These instruments had been fabricated at DRCL to US designs by Dr. C. E. Dahlstrom, who also joined the team and carried out observations at Maralinga. The light output spectrum from each weapon burst was recorded by Glen Turner using special high-speed ciné-spectrographs. These were specially built from a US design by a Canadian company under contract to DRCL.”

In all, Canadians made observations on seven nuclear blasts for the AWRE. By 1959 nuclear-weapon trials were being phased out. The complicated negotiations for an international nuclear test ban treaty began, with the first extended negotiations tak­ing place in the period from 1958 to 1963. The UK conducted its last atmospheric nuclear test blast in 1958, and Canadian participation in UK test blasts ended then too. The US continued with blast trials in the 1960s, and at some of these Canadians researchers were invited to participate.

The expertise that DRCL had built up with respect to thermal measurements was put to use at large conventional-explosives trials (intended to simulate nuclear blasts) conducted at Suffield Experimental Station in the 1960s. For example, Doug Pattman and Parr Tate observed that the thermal pulse from a large high-explosive burst con­sisted of two peaks, somewhat similar to the pulse from a nuclear blast. This was the first time such behaviour was reported for conventional explosives.

Radiac Instrumentation

“Radiac” stands for “Radiation Detection Indication and Computation.” From the beginning of radiation research at DRCL, it was clear that improvements in radiation detection instruments were desperately needed. There were severe problems in procuring suitable equipment from Canadian electronics firms. This was likely due to an absence of expertise in ionizing radiation in Canadian industry, and the failure to realize that in a radiation environment the air itself becomes conductive of electricity and unless precautions are taken, sensitive detection circuits will not behave. Also, the responses of a detector were often quite sensitive to the materials of which it was made. The development of suitable instruments was further frustrated because suitable radiation sources did not exist in industry for proper calibration and measurement of energy response. These problems required a degree of sophistication that Canadian industry could not provide at that time.

DRCL therefore had to build up its own expertise in radiation measurement instruments. DRCL hired scientists and engineers with experience in ionizing radiation, and equipped the laboratory with a range of radiation sources. Some instruments developed elsewhere underwent substantial modification and testing to make them suitable for Canadian military use. When appropriate instruments could not be found, DRCL researchers developed the needed instruments themselves. These activities resulted in five instruments that were accepted into service. When the threat of nuclear war waned, this development program was assigned a much lower priority.

Radiation Physics

This work was under the general direction of Charlie Clifford, and comprised two main areas of interest: the calculation and measurement of the shielding afforded by materials and structures to humans exposed to radiation; and the amount and type of radiation deposited in organs of the human body.

The work on radiation deposition in organs primarily used physical models of the human body (called “phantoms”) with radiation detectors placed in areas known to be sensitive to radiation. The bone marrow and the gut were the two areas of primary interest, as it was known that damage to these tissues is the main cause of rapid death of humans who receive large doses of radiation. This kind of work began in the 1950s and continued into the 1970s. The phantoms were improved to better mimic the human body, and detectors with different sensitivities to radiation were developed (by the Radiation Chemistry Group) for use in the phantoms.

The shielding work also received a significant amount of research attention. One part of the shielding research deserves special mention here, as it made use of a piece of very sophisticated 1960s technology to model and calculate the transport of radia­tion in the air over the ground. That technology was the computer. Parr Tate recalls this novelty:

“In the early 1960s, the transport of radiation in the air over the ground was studied using the computer built by DRTE. In those days, there were no micro-computers, and the existing computers were maintained in industrial or university computing centres, and were not usually available for hands-on operation by scientists. The debugging and successful operation of a program was often a slow and painful process. The early DCBRL [Defence Chemical Biological and Radiation Laboratories, one of DREO’s former names] radiation-transport programs were programmed in machine-language.”

Some of the projects undertaken by DCBRL were: calculating the patterns of radia­tion transport using computer programs, and then conducting tests in the field to confirm the calculations experimentally; determining the shielding afforded by an armoured vehicle to its crew, in the context of a nuclear attack; the transport of radiation down ducts with bends; and calculations of the radiation scattered by slabs of various materials.

Through the work at DRBCL, Canada developed an expertise in radiation shielding that resulted in an international reputation. First Charlie Clifford, and then Frank Szabo, were members of the Radiation Shielding Committee of the US Academy of Sciences, a prestigious membership. The work at DRBCL has now become classic and is included in standard shielding handbooks.

Radiation Biology

The earliest work in radiation biology was begun by Paul Vittorio at Defence Research Kingston Laboratoies (DRKL), studying the changes in organs exposed to radiation. This work was transferred to DRCL when DRKL was closed.

Efforts in radiation biology later turned to the search for radioprotective agents, that is, compounds which when injected into the body afford a degree of protection from subsequent exposure to radiation. George Grant directed much of this work, often in cooperation with similar work done by other nations, particularly at the Walter Reed Army Institute of Research in the US. Various candidate compounds were tested by injecting them into mice, exposing the mice to various doses of radiation, and observing their survival rate. Jack Purdie studied the effect of radioprotective agents on irradiated cells in tissue culture. Some of the compounds tested were synthesized at DRCL.

Despite these efforts, it was eventually recognized that radioprotective compounds could never be as effective as we needed them to be—you could only get so much compound into the bone marrow, and this was not enough to prevent the number of lesions produced by radiation. Research in Canada and in several other countries took a new direction: the study of radiation-induced vomiting. After even non-lethal doses of radiation a human vomits and if this occurs during certain military tasks it can render the soldier militarily unfit. Even if the dose is lethal, it might not be immediately so, and there would be a military advantage to keeping the soldier functional as long as possible. Alan Cairnie took up research on the causes of radiation-induced vomiting and of possible means of preventing it.

Cairnie’s experimental design is representative of the type of ingenuity required in laboratory research. He used the rat as a model, though rats don’t actually vomit. Researchers did note that rats avoid foods that they associate with an unpleasant gastric effect, analogous to vomiting. In this way the avoidance of foods that were associated with an irradiation effect would indicate to the experimenter that this “vomiting analogue” was present. And then certain drugs could be tested to see if this effect was reduced. Research in this area by Canada and other NATO nations through the 1980s has facilitated the development of anti-nausea drugs now used by cancer patients undergoing radiation therapy.