Assessment of the Jabiluka Project : report of the Supervising Scientist to the World Heritage Committee
Johnston, A.; Prendergast, J. B.; Bridgewater, Peter
E-Publications; E-Books; PublicationNT; Supervising Scientist Report; 138
Alligator Rivers Region
Main report--Appendix 2 of the Main Report. Submission to the Mission of the World Heritage Committee by some Australian Scientists ... --Attachment A. Johnston A. and Needham S. 1999. Protection of the environment near the Ranger uranium mine--Attachment B. Bureau of Meteorology 1999. Hydrometeorological analysis relevant to Jabiluka--Attachment C. Jones, R.N., Hennessy, K.J. and Abbs, D.J. 1999. Climate change analysis relevant to Jabiluka--Attachment D. Chiew, F and Wang, Q.J. 1999. Hydrological anaysis relevant to surface water storage at Jabiluka--Attachment E. Kalf, F. and Dudgeon, C. 1999. Analysis of long term groundwater dispersal of contaminants from proposed Jabiluka mine tailings repositories--Appendix 2 of Attachment E. Simulation of leaching on non-reactive and radionuclide contaminants from proposed Jabiluka silo banks.
Uranium mill tailings - Environmental aspects - Northern Territory - Alligator Rivers Region; Environmental impact analysis - Northern Territory - Jabiluka; Uranium mines and mining - Environmental aspects - Northern Territory - Jabiluka; Jabiluka - Environmental aspects
Supervising Scientist Report; 138
1 volume (various pagings) : illustrations, maps
https://hdl.handle.net/10070/462403; https://hdl.handle.net/10070/462400; https://hdl.handle.net/10070/462405; https://hdl.handle.net/10070/462406; https://hdl.handle.net/10070/462408; https://hdl.handle.net/10070/462409; https://hdl.handle.net/10070/462411
57 Table 5.3.1 Estimates of the maximum concentrations of the prinipal constituents in runoff from the ore stockpile at Jabiluka Chemicals Concentration mg/L Radionuclides Concentration Bq/L Uranium 80 238U 1000 Magnesium 500 234U 1070 Sulphate 2,000 230Th 3 226Ra 340 210Pb 20 210Po 3 ERA estimated that the electrical conductivity, dominated by magnesium and sulphate ions, would be in the range 30005000 S/cm. The upper limit of this range corresponds to concentrations of magnesium and sulphate of 500 mg/L and 2000mg/L respectively. The Supervising Scientist has recently carried out solute modelling for the waste rock dumps at Ranger (leGras & Klessa 1997). This work showed that MgSO4 mobilisation occurs at a rate similar to the rate of erosive degradation of the schist. That is, there is an initiation period after rock placement of about 3 years during which little solute is released. According to the proposed Jabiluka mine plan, ore and waste rock will be stored for an insufficient period for significant solute evolution. The Supervising Scientist, therefore, believes that the concentrations of Mg and SO4 that will occur in runoff from the ore stockpile at Jabiluka will be significantly lower than the estimates provide by ERA. Neverthless, to ensure that a conservative estimate is obtained in the risk assessment, the concentrations of MgSO4 have been taken to be the highest values estimated by ERA. A summary of the concentrations of the principal constituents in runoff from the Jabiluka ore stockpile used in the risk assessment are provided in table 5.3.1. It is stressed that all of these concentrations are considered to be maximum expected values and some are likely to be significant over-estimates. 5.3.2 Radiation exposure of members of the public The probability of exposing members of the public to a particular radiation dose can be derived from the probability with which a specified volume of water will, under extreme climatic conditions, need to be discharged to Swift Creek downstream from the mine and the calculation of the radiation dose that will result from that discharge. As stated in section 5.2.3, the storage capacity of the retention pond proposed by ERA in the PER was 810,000 m3. From the results of the Monte Carlo simulation methods shown in figure 5.2.1, the probability of the occurrence of water volumes in excess of the pond capacity can be derived. These results are shown in figure 5.3.1. Estimates of radiation exposure of members of the public resulting from discharges of radionuclides in water from the Ranger mine have been made by the Supervising Scientist (Johnston 1990) based upon a model of dispersion of radionuclides in the Magela Creek system, the diet of the critical group, and results of research on the uptake of uranium series radionuclides in food items from the waters and sediments of the Magela system (Johnston et al 1997). The model has recently been updated by Martin et al (1998) to take into account all recent research results and the most recent recommendations of the International Commission on Radiological Protection on dose conversion factors (ICRP 1996).
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