Supervising Scientist Division

Supervising Scientist Annual Report 2003 - 2004

Supervising Scientist, Darwin, 2004
ISBN 0 642 24391 3
ISSN 0 158-4030

2 - Environmental assessments of uranium mines (continued)

2.2 Ranger (continued)

2.2.5 Contaminated vehicle incident

Energy Resources of Australia (ERA) advised the Assistant Secretary of the Office of the Supervising Scientist by telephone on 5 February 2004 that an incident had occurred in which two small earth-moving vehicles, called 'bobcats', had been returned in a mildly contaminated condition to the workplace of the Community Development Employment Project (CDEP) in Jabiru. Written notification of the incident was provided by e-mail on the following day. The telephone notification described the contaminated material as being of 'low activity' and the incident was initially treated as being of a relatively minor nature.

On 29 March 2004, the Supervising Scientist was informed by a staff member of the Gundjeihmi Aboriginal Corporation that the manager of the CDEP was concerned about the incident and wished to meet with the Supervising Scientist to discuss the issue. The Supervising Scientist met with staff of CDEP on 30 March 2004 and, following discussion of the CDEP concerns, agreed to investigate the incident and to provide a report on completion of the investigation.

The investigation has revealed that there were at least three occasions on which vehicles left the Ranger minesite without adequate radiation clearance during 2003 and 2004. The Supervising Scientist investigated the circumstances under which these vehicles left the Ranger mine and assessed the likely impact on the health of members of the public who were exposed to radioactive material contained on these vehicles.

Radiation clearance procedures at Ranger

The Supervising Scientist has concluded that radiation clearance procedures at the Ranger mine are inadequate. This conclusion is based upon the following failure of procedures identified during the investigation:

Radiation clearance procedures at Ranger need to be reviewed and upgraded to include much more specific instructions on the cleaning and inspection of vehicles and the inclusion of gamma dose rate monitoring equipment. These procedures should be the subject of a regular, independent audit process.

It has also been concluded that all staff involved in radiation clearance procedures need to be adequately trained in all practical aspects of radiation clearance and that ERA should review its procedures for the monitoring of the movement of vehicles on site to ensure that all vehicles that have been in controlled areas are checked for radiation clearance certificates at the Security Gate.

Two key groups involved in these incidents, the CDEP staff who carried out the maintenance work in the leach bunds and the staff who are responsible for security at the Ranger mine, were contractors rather than ERA staff. It is the Supervising Scientist's view that ERA should review the use of contracted labour at the Ranger mine within a risk assessment framework to ensure that its key responsibilities for the protection of people and the environment are not jeopardised by the employment in key areas of staff over whom ERA has little or no direct control.

Radiation exposure of members of the public

One of the incidents investigated resulted in the deposition of a relatively large quantity of partially leached uranium ore from the Ranger mine in two areas of the CDEP yard in Jabiru. This resulted in the exposure of members of the public (the CDEP mechanic and his children) to low levels of radiation over a period of several months.

Estimates have been made of the radiation dose received by these members of the public as a result of this incident. It has been concluded that the radiation dose received by the mechanic and his children was of the order of 1 mSv. It is not possible to be more precise but it is more likely that the actual dose received would have been less than rather than more than 1 mSv.

The annual dose limit for members of the public (excluding radiation doses from medical procedures) is 1 mSv above natural background. Hence, these radiation dose estimates imply that this limit may have been exceeded as a result of this incident. However, the conservative assumptions made in the calculations lead to the conclusion that it is more likely that the dose was smaller than 1 mSv.

It needs to be stressed that a radiation dose of 1 mSv does not present a significant health risk. For comparison, the average annual radiation dose received by Australians from natural background sources is approximately 2 mSv per year. Also, some diagnostic x-ray procedures deliver several mSv to the patient. Following the completion of these dose estimates, the SSD Health Physicist counselled the CDEP mechanic and his wife and reassured them that whilst this incident should not have occurred and the radiation exposure of the mechanic and his children was an unacceptable consequence, no adverse health effects were likely as a result.

Radiation protection culture at Ranger

The concentrations of radionuclides in material at Ranger uranium mine are, given the average ore grade of about 0.3%, relatively low in comparison with some other mines in the world and are certainly low when compared with concentrations that occur in other parts of the nuclear fuel cycle. Hence, provided that a carefully designed radiation protection regime is in place and is implemented with diligence, it should be relatively easy to ensure that incidents that involve significant radiation exposure of employees or members of the public do not occur. The record at Ranger over the first 20 years of operations has demonstrated that this is so.

There have, however, been three such incidents in the past two years at Ranger. The first incident involved the exposure of workers who were replacing the roof of the precipitator building at the minesite in November 2002. The most exposed individual in that incident was estimated to have received a radiation dose approximately equal to the radiation exposure limit for workers.

The second incident was the potable water contamination incident that occurred on 23-24 March 2004. This incident was recently investigated by the Supervising Scientist and it was concluded that the maximum exposure of workers was likely to have been very much less than the radiation exposure limit for workers.

In the current incident, exposure estimates for members of the public are approximately equal to the dose limit for members of the public.

In addition to these incidents where actual exposure of workers or members of the public has taken place, there have been a number of occasions over the past two years on which the Supervising Scientist has expressed concerns about incidents in which ERA failed to carry out monitoring specified in either the Ranger or the Jabiluka (also operated by ERA) Authorisations.

Further, in the recent Audit of performance of ERA against the Draft Mining Management Plan (MMP) for Ranger, it was identified that dust monitoring of an operator in the crusher control room and personal dust monitoring in the acid control room were not undertaken despite there being commitments in the MMP that this monitoring would be carried out.

It is the Supervising Scientist's view that the recent occurrence of radiation exposure incidents and the failure to carry out monitoring that is required under the Ranger and Jabiluka Authorisations has been due, at least in part, to a change in the culture of radiation protection within ERA. There is also evidence that insufficient resources have been allocated by ERA to radiation protection over the past two years.

It appears that complacency has characterised the ERA approach to radiation protection in recent years. That this is so is borne out by a number of the comments from the ERA reports examined in the investigation which demonstrate that the significance of the incident was generally downplayed and that it was simply assumed that no significant radiation exposure had occurred without an appropriate measurement programme or adequate estimation of radiation dose.

The Supervising Scientist has concluded that ERA should immediately implement a programme to bring about a change in the radiation protection culture at Ranger and that ERA should review the resources allocated to radiation protection at Ranger and ensure that they are adequate to meet all of the requirements specified in the Environmental Requirements and under Northern Territory law.

Environmental Requirements and the Ranger General Authorisation

Energy Resources of Australia (ERA) is required to comply with the Commonwealth Environmental Requirements (the ERs) for the Ranger mine as attached to the Authority issued under Section 41 of the Commonwealth Atomic Energy Act 1953 and to the export permit for uranium granted under the Customs (Prohibited Exports) Regulations 1958.

The Supervising Scientist has reviewed the extent to which ERA may have been in breach of the Ranger Environmental Requirements. It has been demonstrated that the transport of contaminated material in a vehicle from the Ranger mine resulted in radiation exposure of a member of the public and his children. While the estimates of the doses received are slightly greater than the annual dose limit for members of the public, the uncertainties in these estimates are such that it could be difficult to establish in a court of law that the dose limit had certainly been exceeded.

However, it has been demonstrated that the radiation clearance procedures adopted at Ranger were inadequate in a number of ways and that the radiation exposure of members of the public could have been avoided if reasonable, best practice procedures had been in place at Ranger. The Supervising Scientist has, therefore, concluded that the radiation doses received by members of the public were not 'as low as reasonably achievable' and that this constitutes a breach of Environmental Requirement 5.1.

It has been concluded that since the radiation clearance procedures in use at Ranger were inadequate to ensure the protection of the health of members of the regional community, ERA has also been in breach of ER 1(c) and ER 12.1. The Supervising Scientist has also concluded that it could be strongly argued that ERA has not employed adequate numbers of competent, appropriately qualified and experienced staff to ensure that it can provide the required level of protection of human health and that ERA may have been in breach of ER 14.1.

The Supervising Scientist has therefore concluded that the Commonwealth Government should consider whether action should be taken by the Commonwealth in response to the established breach of Environmental Requirements 1, 5.1 and 12.1.

The report of the Supervising Scientist's investigation into the incident will be provided to the Minister for the Environment and Heritage early in 2004-05.2

Footnote:
2 Supervising Scientist 2004. Investigation of radiation clearance procedures for vehicles leaving the Ranger mine. Supervising Scientist Report 185, Supervising Scientist, Darwin NT.

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