43

How much waste is already stored at ANSTO? 

ANSTO holds about 1 250m³ of LLW and short-lived intermediate level waste, including items such as laboratory equipment, lightly contaminated clothing, paper and glassware. 

ANSTO holds approximately 220m³ of long-lived intermediate level waste, including target cans, alumina columns, used control arms, aluminium end pieces, and solidified liquid waste from radiopharmaceutical production.  In addition, about 165 m³ of historic thorium residues, principally from mineral sands processing and uranium oxide residues are held at ANSTO. 

Most of ANSTO's wastes are low level, but small quantities of intermediate level wastes are also generated.  Typically, ANSTO produces 150 drums (200L capacity) a year of low level solid waste, two cubic meters of solid intermediate level waste, 500 litres of intermediate level liquid waste and a quantity of liquid effluent waste. 

Intermediate level liquid waste results from the dissolution of irradiated uranium dioxide pellets.  Molybdenum-99 is extracted from the other fission products in this solution for purification and placement in generators for medical use.  The molybdenum-99 in these generators decays to technetium-99m, which is then used in numerous diagnostic medical applications.  The remaining solution from the initial extraction is handled as intermediate-level liquid waste.  This is then processed to produce a solid product, which constitutes a much smaller volume than the liquid waste did.  A further project to incorporate this waste into a stable matrix, allowing it to be safely stored for an indefinite period, is under way at ANSTO. 

ANSTO also generates liquid effluent waste from the sewer, labs, workshops, cooling towers and radioisotope production areas.  Approximately 100 000 m³ of waste water, of which approximately 5 000 m³ contains very low levels of radioactivity, are generated each year.  This waste water is collected in tanks, analysed and treated where necessary to remove contaminants.  The water is discharged through the sewer to Cronulla Sewage Treatment Plant after meeting the discharge limits set by Sydney Water.  The waste water must meet World Health Organisation Drinking Water standards for radioactivity at Cronulla Sewage Treatment Plant. 

Some operations at ANSTO produce airborne discharges.  Charcoal traps, high efficiency filters and scrubbers are used to remove fine particles or gaseous nuclides prior to discharge.  These devices then become part of the solid waste stream. 

Monitoring of airborne releases is on a continuous basis, and ANSTO has four sampling stations at its site boundary.  Independent checks are carried out by ARPANSA.  Away from the ANSTO site (which is surrounded by a 1.6 kilometre buffer zone), the levels of radioactivity in the air are too low to be measured. 

A special computer model developed to use wind information gathered over the years to calculate radiation doses at various off-site locations shows the annual doses to the community are significantly less than 0.01 mSv per year - that is, significantly less than one per cent of the allowable 1mSv per year dose limit for the general community. 

The procedures used to process and monitor radioactive waste are strictly controlled.  ANSTO is subject to stringent regulation by its independent statutory regulator, ARPANSA.  ANSTO also continually carries out environmental monitoring, and publishes a comprehensive environmental and effluent monitoring public report each year.  The levels of radionuclides in the environment from ANSTO's operations have always been very low and have never had radiological significance.