The Maralinga Cobalt 60 Incident




In 1957 the British Government carried out a series of 3 atomic weapons tests at Maralinga in South Australia known as the "Antler" series. These tests were known individually as Biak, Tadje, and Taranaki. Biak and Tadje were tower mounted shots, and Taranaki was suspended from a balloon.

Following each explosion, nuclear radiation surveys were carried out by the Australian Health Physics Group (AHP). In the period immediately after the blasts, these surveys were carried out at very frequent intervals, but as the radiation gradually decayed, the period between the surveys gradually increased. In order to ensure repeatability, the actual measurements were carried out at the same points each time. These measurement points were on 12 radiating lines from the ground zero point, and were spaced at 100 foot intervals along each radiating line. The measurement points were marked by a wooden peg driven into the ground. Generally the measurements were done by an AHP staff member walking along the radiating lines while carrying various types of instrumentation. Generally they would walk out along one line, then in along the next line, and so on. The measurements would be recorded on pre-printed forms on a clip board.

Using the information from the radiation surveys, radiation level contour maps were drawn up by AHP staff. These maps were used as a guide to determine safe areas, etc. However, because the measurements were only taken at the pre-marked measurements points, there were large areas within the affected area between the radiating lines where measurements were not taken.

Initially the contour lines for all blast sites were reasonably uniform. However, as time passed, and the general radiation levels began to subside as the shorter half life elements decayed, the contour lines for the Tadje site started to show abnormalities in a northerly direction from ground zero. Initially these abnormalities were not sufficiently obvious to raise any alarms.

About 9 months after the Tadje explosion, one of the AHP staff, Mr Doug Rickard was doing some surveys at the Tadje site. Contrary to the normal practice of crossing between lines only at the extreme end of the survey line, Mr Rickard crossed between the survey lines at about the 700 foot point. As he traversed this previously unsurveyed area, Mr Rickard noticed abnormal levels of radiation activity which attracted his interest. In particular, one of the abnormalities was that the radiation seemed to be in very discrete spots, and not evenly distributed as normal fallout would have been.

The other abnormality was that Mr Rickard was using an Alpha particle measuring instrument. Normally an Alpha particle counter has to held within 1 to 2 cm of the source to be measured, but Mr Rickard was at that time holding the sensing head at waist level as he walked along, yet was still observing high readings.

Using his right foot (in rubber boots) Mr Rickard found he was able to move the actual source of radiation. Using a standard binary search technique, Mr Rickard was able to isolate the source of radiation to about a handful of sand. A visual inspection of this small sample revealed a small (2-3 mm) shiny black metallic looking spherical pellet totally unlike any of the standard desert surface. This metallic pellet proved to be the source of radiation.

Continuing this technique, Mr Rickard was able to recover approximately 30 similar metallic particles which were stored in the standard specimen collection container (Dr Pat tobacco tins.....) It was obvious from his instruments that there were many many more such sources, but there were far too many of them for him to collect at that time. Mr Rickard placed the containers in the back of his Land Rover and drove the 36 miles back to the RB (Radio Biological) laboratory area where the AHP offices were located.

When he arrived back at the laboratory area, Mr Rickard found that the other AHP staff were running around in some consternation, as much of the laboratory instrumentation had suddenly gone haywire coincident with his arrival. A gamma measuring instrument was obtained and a measurement of just one of the pellets showed a reading equivalent to about 30 millicuries. This confirmed that these pellets were indeed very strong gamma emitters, and the readings Mr Rickard had obtained on the alpha instrument has been actually due to malfunction of the instrument in such a high gamma field.

In order to ascertain the composition of the pellets, a Pierson scanning gamma spectrometer was used which used a sodium iodide scintillator. Just one pellet alone was so strong that the instrument was overloaded. Finally the pellet had to be moved onto a wooden stool about 30 feet away outside the building before accurate readings could be obtained. The characteristic double curve obtained confirmed that the material was Cobalt 60 (Co60).

An attempt was made to measure the volume of one of the pellets. To do this, a calibrated pipette was about half filled with water, and then the pellet was dropped into the pipette to measure the change in water levels. The level of activity from the pellet was such that it caused blackening of the glass pipette from a phenomenon known as F-centre displacement.

On 10-July-1958, the AHPR, Mr H Turner reported to the AWRE - 'A number of Co60 pellets have been found in the vicinity of 700 feet North of Tadje with an average activity of 40 millicuries, repeat millicuries. The largest pellet (79mC) would register 36 r/hr when touching a 1390. The potential lethality of each pellet is increased by the fact that they are only 1 to 2 m.m. in diameter and could easily be lodged in clothing or be ingested.' (1)

The most immediate response to Mr Turner's report was an immediate and complete security clampdown. Even though an Australian citizen working in Australia, Mr Rickard was taken to a British security officer who warned him very strongly not to talk about the incident to any other Australians, even his superior, Mr OH Turner.

The extremely sensitive political nature of the event was evident in an AWRE letter dated 23-July-1958 - 'I mention these items to you because there is a danger that some political trouble will arise if these stories get a wide circulation.' (1) It was evident that the Australian people, and even the Australian government, were being kept very much in the dark regarding some of the activities going on at Maralinga.

Mr Rickard had been wearing a standard issue film badge when he discovered the Cobalt 60 pellets. However when the film badge was developed it had been so saturated with radiation that it was totally black and it was impossible using the available equipment to determine just how much gamma radiation Mr Rickard had received.

The AWRE requested that the Cobalt 60 should be collected as soon as possible. Special lead containers were flown out from the UK for this purpose. Unfortunately, because of handling the pellets, most of the AHP staff by this time had already received the Maximum Permissible Level (MPL) allowed, so were not in a position to be able to carry out the collection process.

At that time, a number of Australian defence services personnel had arrived at Maralinga for training in radiation detection techniques. These personnel were used to collect as many of the pellets as possible. Because of the security restrictions, they could not be told of the nature or danger of the material they were collecting. A number of scoops were fabricated by affixing jam tins onto long wooden handles, and these were used by the collectors so as to maintain at a reasonable distance from the pellets. Some of the pellets were so small that they had to be collected using tweezers. Some of the personnel who had been performing the collection using tweezers later reported their fingers being red around the tips and nails.

Because of the high level of activity of the pellets, and their discrete nature, it was possible to collect the majority of the Cobalt 60 pellets from the Tadje site.

Again on 01-December-1958, Mr Turner reported to the AWRE - "During July to October 1958, 180 Co 60 pellets totalling approximately 4.5 curies have been recovered from an area of about 100,000 square feet North of Tadje ground zero..." (1)

The presence of the Cobalt 60 at the Tadje site had not been advised to the AHP group, but Prof Sir E Titterton, Chairman, Atomic Weapons Tests Safety Committee (AWTSC), HAD been advised prior to the test of the presence of Cobalt 60. He chose not to pass on the information to the AHP group. "When asked why he did not pass on to Turner the information about the cobalt 60, Titterton said they wanted '...to give Harry [Turner] and his workers a bit of a test'...".(1)

The Royal Commission report, section 9.5.5 states - " It was of great concern to the AHPR that the discovery of the cobalt-60 had been accidental. It appears that other Australian authorities were also ignorant about the use of cobalt-60. Richardson of CXRL, the Senior Health Physics Advisor to whom Turner reported administratively, wrote to Turner on 12 August 1958 -
'The discovery of the cobalt is disturbing...... We can do little about this until we receive a reply from the UK.'" (1)

It was therefore by the deliberate action of Prof Titterton in withholding the important information regarding the presence of Cobalt 60 at Tadje from Mr Richardson, Mr Turner, and the AHP group, that Mr Rickard received his damaging dose of gamma radiation. This might be interpreted as 'criminal negligence'.

In the 9 year period following his exposure to the Cobalt 60, Mr Rickard experienced many varied and odd medical problems. These included the loss of skin on his right foot (the foot used to isolate the Cobalt 60 pellets), severe pain in the right foot, loss of skin on right and left hands, etc etc. In 1967 at the Royal Brisbane Hospital Mr Rickard was finally diagnosed at age 27 with 'chronic myelofibrosis and myeloid metaplasia'. Myelofibrosis is normally only a disease of the aged, and the prognosis is normally two to three years. Mr Rickard was advised that his life expectancy was therefore not good.

Mr Rickard's health remained reasonable until about 1980 when he started to suffer recurring bouts of severe pain in the left abdomen. In 1982 this was determined by doctors at the Royal North Shore Hospital in Sydney to be due to an enlarging spleen, a characteristic of myelofibrosis. His spleen continued to enlarge over time, until in 1992 the spleen had reached a point where he was in continuous pain and the spleen itself was in danger of rupturing. His spleen was removed in 1992 at the Mater Hospital in Brisbane and weighed 1800 grams, in comparison with the approximately 100 grams of a normal spleen.

Since the removal of his spleen, Mr Rickard's liver has taken over the blood production function, and it too is now enlarging. With the loss of his spleen, Mr Rickard's blood chemistry altered dramatically. The platelet count rose to such a high level that in early 1993 Mr Rickard suffered two mild thrombosis. He is now being treated with alpha-interferon in order to reduce the platelet count, and to help improve immunity. He is also permanently on morphine to alleviate the pains from the enlarged liver.

At current age of 60 (1999), Mr Rickard is now the longest surviving patient with myelofibrosis in the world. As such, it means that there is no precedence or prehistory of this stage of the disease to help in its treatment. This greatly hinders the medical staff who are currently treating Mr Rickard.

There also remains the question of the long term medical history of the Australian services personnel who were used to clean up the Cobalt 60 from the Tadje site, and were follow up health studies ever conducted on them?

Bibliography:-

(1) The Report of the Royal Commission into British Nuclear Tests in Australia Volume 1 Section 9.5 'The Cobalt-60 Incident'. Australian Government Publishing Service.


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