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RADIATION SAFETY MANUAL
Section 6: Disposal of Radio Active Waste

INDEX
6.0 General
6.1 Categories of Waste
6.2 Aqueous Waste
6.3 Radio Immunoassy/125Iodine Counting Waste
6.4 Disposal of Radioactive Waste Via Sewage
6.5 Long Term Storage
6.6 Responsibility for Stored Waste
6.7 Non-Aqueous (Organic) Liquid Waste  
6.8 Solid Waste
6.9 Disposal Limits

6.0 GENERAL
Waste disposal is the responsibility of the generator (the person carrying out the procedures with the isotopes) of the waste.

(The appropriate Guideline for disposal of waste in New South Wales is the EPA document "Environmental Guidelines: Assessment, Classification & Management of Liquid and Non-liquid Wastes (1999)".)

Residues of radioactive materials and wastes arising from work with such materials are known as radioactive wastes. Such wastes shall be disposed of in accordance with appropriate radiation and waste disposal legislation (EPA).

As a general guide, radionuclides may be discharged from an institution only in quantities low enough such that the waste can be treated according to its constituent category and not as radioactive waste and any other relevant constraints in the Radiation Control Act (1990) and the Regulation (2003) are not exceeded. The current limit is a specific activity of 100 becquerels per gram or ml.

Where more than trace quantities of unsealed radioactive materials are in constant use in laboratories, discharge authorizations for solid, airborne and liquid effluents shall be negotiated with the appropriate local regulatory authorities.

Radioactive wastes of short half-life should be stored in a safe place and allowed to decay, or be diluted so that their activity is reduced to 100 becquerels per gram (or ml.). They can then be discarded as inactive waste according to the EPA category for the actual material constituting the waste (this will usually be "industrial"). Account shall be taken of any longer-lived decay products. Labels and warning signs should be removed from containers before they are consigned as garbage. Nevertheless the University recommendation is that this waste still be transported to a central facility ( the “Radiation Bunker” at the Callaghan Campus” ) where disposal by a professional waste disposal company will be arranged by the University Radiation Officer at the generators expense. Material deposited at the Bunker for decay will not be accepted unless labelled with name, date, isotope, estimated time for 10 half lives.

6.1 CATEGORIES OF WASTE
The following is an excerpt from the EPA guideline.

"Section 3.5 Classification of wastes containing radioactive substances"

Wastes containing any natural or artificial substance that emits ionising radiation spontaneously must be classified on the basis of both their radioactive and other characteristics, according to the stepwise procedure defined below:

  1. The radioactivity of the waste must be assessed in accordance with the Radiation Control Act 1990 and the Radiation Control Regulation 2003.
  2. If the liquid or non-liquid waste has a specific activity greater than 100 becquerels per gram and consists of or contains more than the prescribed activity of any radioactive element listed in Schedule 1 of the Radiation Control Regulation 2003, whether natural or artificial, it must be classified as hazardous waste.
  3. If the liquid or non-liquid waste has a specific activity of 100 becquerels per gram or less and/or consists of or contains equal to or less than the prescribed activity of any radioactive element listed in Schedule 1 of the Radiation Control Regulation 2003, whether natural or artificial, then the total activity ratio and the specific activity ratio must be calculated according to the mathematical expressions given below:

    The total activity ratio is calculated using the expression:

    Total activity ratio = (A1 x 10-3) + (A2 x 10-4) + (A3 x 10-5) + (A4 x 10-6) where A1 to A4 are the total activity of Group 1 to Group 4 radionuclides, as set out in Column 1 of Schedule 1 of the Radiation Control Regulation 2003.

    The specific activity ratio is calculated using the expression: Specific activity ratio = SA1 + (SA2 x 10-1) + (SA3 x 10-2) + (SA4 x 10-3) where SA1 to SA4 are the specific activity (of the material) of Group 1 to Group 4 radionuclides, as set out in Column 1 of Schedule 1 of the Radiation Control Regulation 2003.

    Specific activity is defined in the Code of Practice for the Safe Transport of Radioactive Materials, 1990, which is referenced in clause 23 of the Radiation Control Act 1990.

    Specific activity of a radionuclide means the activity per unit mass of that nuclide. The specific activity of a material shall mean the activity per unit mass or volume of the material in which the radionuclides are essentially uniformly distributed.

    The total activity of a material means the activity of the whole of the material in which the radionuclides are essentially uniformly distributed (determined using 1-kilogram representative samples of the whole material).

  4. If the specific activity ratio, or total activity ratio, is greater than one, then the waste must be classified as follows:

    Liquid wastes must be classified as hazardous waste.

    Non-liquid wastes must be classified as industrial waste unless other characteristics of the waste mean that it must be classified as hazardous waste (for example, it may be classified as hazardous waste because it matches another one of the hazardous waste types or streams or it may contain chemical contaminants that will lead to its assessment as hazardous waste according to the chemical assessment procedure.

  5. If the specific activity ratio and total activity ratio are equal to or less than one, then the waste must be classified as follows:

    Liquid wastes must be classified according to their other characteristics (ignoring their low-level radioactivity), in accordance with the normal liquid-waste assessment and classification procedure specified in Section 3.

    Non-liquid wastes must be classified according to their other characteristics (ignoring their low-level radioactivity), in accordance with the normal non-liquid-waste assessment and classification procedure specified in Section 3."

    Management of radioactive waste at the University of Newcastle requires that at the point of generation the waste must be separated into its various categories. That is Liquid and Solid Waste, High and Low Activity, Aqueous Liquid and Organic Liquid, Radioimmunoassay/125Iodine counting waste.

6.2 AQUEOUS WASTE
Aqueous Waste that can be disposed of by the sink in the Radiation Room
Low activity aqueous waste, eg tritium, carbon 14, calcium 45, sulphur 35, where the specific activity can be assessed as below 100 becquerels per ml can be disposed of immediately down the designated drain but a record must be maintained of the amounts disposed to the sewer so that a daily/weekly disposal rate can be assessed. Higher activity aqueous waste should be allowed to decay before disposal, eg Phosphorus 32, Iodine 125, Chromium 56. If aqueous waste will decay to an acceptable level within one month, then the waste may be stored in the Building’s Radiation Room, however if the time is longer it should be allowed to decay in the local Radiation Bunker. You should contact your Building/Local Radiation Safety Officer for advice. Containers can only be placed in the Bunker if accompanied by a label indicating the name of the waste generator, the laboratory from which the waste came, the isotope, its half life and date when the calculated specific activity of the container will be 100 becquerels or less.

6.3 RADIO IMMUNOASSY/125IODINE COUNTING WASTE

 6.3.1  

Iodine-125 counting waste (vials) may be disposed of as normal pathology waste as long as the specific activity of the package remains at 100 becquerels per gram or less.

NB Consideration must also be given to any BIOHAZARD implications which may impinge on the disposal of human or animal waste for radioimmunoassay procedures. Guidelines for inactivation of bacteria and viruses must also be followed.
 6.3.2  Radioimmunoassay Waste
1. Vials and tubes used for gamma counter samples may normally be discarded as non-radioactive waste as the activity is so small as to be negligible. However the calculation of specific activity must still be done to ensure the limit of 100 becquerels per gram is not exceeded. These calculations should be maintained as part of the waste disposal record for that isotope.
2. Do not mix RIA and liquid scintillation waste in the same container.
3. RIA waste should not be labelled as radioactive when discarded.
4. Do not accumulate large quantities of sample tubes as the total activity could approach significant levels.
5. Guidelines for disposal of contaminated waste should be followed if appropriate.
6.

The University recommends that all waste be disposed of through a professional waste disposal company who can ensure that all regulations pertaining to the disposal of waste in NSW are properly complied with. This can be organised on a Building/Research Unit basis or be transported to a central location where the University Radiation Officer will organise disposal at the generator's expense.

6.4DISPOSAL OF RADIOACTIVE WASTE VIA SEWAGE
As indicated above, low level liquid waste may be discarded via those sinks labelled for the disposal of radioactive materials. Disposal of small amounts of radioactive material via laboratory sinks is possible if the following guidelines are strictly adhered to:

  1. Any sink used for disposal of radioactive waste must be clearly marked as such, and only used for that purpose.
  2. Only soluble radioactive material may be disposed of via sinks.
  3. When waste is disposed of via a sink, it should be flushed with copious amounts of water.
  4. Scintillation and other flammable fluids must not be disposed of via sinks as this represents a major fire and explosion hazard.Carrier-free material or material of high specific activity (even though the total activity may be low) should be mixed with a large quantity of non-radioactive carrier before disposal. Where possible, the carrier should be of the same chemical form as the waste. If this is not possible, then the carrier should be in an inorganic form.

  5. The specific activity of material that is disposed of in this way must remain at 100 becquerels per ml. or less and a record kept of the calculations and date of disposal.

6.5 LONG TERM STORAGE
Waste that cannot be disposed of quickly (within 1 month) is no longer able to be handled centrally by the University if transport to the bunker involves road travel on public roads. The limit per package for transport is the same as that for disposal, 100 becquerels per gram. In addition determine whether the package can be classified as an “Excepted Package”. For this classification:

(If the package does not comply with the “Excepted Package” criteria, then the transport must comply with the full requirements of Type A or Type B packages. If there is doubt as to the compliance of a package, seek the advice of the Radiation Protection Officer.) Once the material has decayed to a safe level then it can be disposed of, or transported to the central site for disposal. For this purpose a special Radioactive Waste Storage Shed has been constructed and is under the control of the University Radiation Safety Officer, Dr David Kay of the Faculty of Science and Information Technology.

Waste that requires professional disposal or storage that is generated on the Callaghan Campus can be transferred to the Radioactive Waste Store. Each item stored must be identified as in 6.6 below and details entered into the register maintained in the Waste Store. The final disposal will be organised by the University Radiation Officer and if expense is incurred, the appropriate school will be billed.

Disposal of any contaminated waste by a professional waste disposal company is extremely expensive and so as much as possible should be handled ourselves. Particularly with respect to solid waste (eg gloves, tissues, some plastic ware) and aqueous waste, if there is a possibility that it will decay sufficiently for release to the environment within a few months then it should be stored in the Radioactive Waste Shed and then disposed of.

The Radiation Safety Officer has further information on levels of activity that can be released to the environment. If in any doubt, the Radiation Safety Officer must be consulted before proceeding.

6.6 RESPONSIBILITY FOR STORED WASTE
It is the generator's responsibility to ensure any stored waste must be marked with his/her name, the name of the isotope used, the date of the experiment, an estimation of the total amount of activity being stored, half life and the estimated time of disposal. It is the responsibility of the generator of the waste to make a note of the disposal date and to ensure that it is disposed of after checking levels of activity with the appropriate monitor.

6.7 NON-AQUEOUS (ORGANIC) LIQUID WASTE
Non-Aqueous (Organic) Liquid Waste cannot be disposed of in the sewerage system. Organic liquid waste should be poured into a designated plastic container in the Building Radiation Room. The container must be marked with each different organic liquid added and the various contaminating radioisotopes indicated. The person who finally fills the container must arrange for its removal to the Radioactive Waste Storage Shed. If no suitable plastic containers are available a limited number are available from the University Radiation Safety Officer. If possible any organic liquid waste containing chlorinated hydrocarbons should be separated from other organic liquids.

6.8 SOLID WASTE
At the point of generation, separation must be made into high and low activity waste. Any glassware or other utensils that are to be reused should be immediately soaked in a decontaminating solution. Disposal of low level waste that is not marked as radioactive can be bagged and if levels are below that of 100 becquerels, can be released to the environment i.e. normal garbage system. Any marked waste or high level waste must be bagged and labelled with:

1. User's Name
2. Date
3. Type of Isotope
4. Level of Activity
5. Half life
6. Expected date of disposal

Again with isotopes that have short half lives that would allow decay to a level permissible for disposal, it is the generator's responsibility to ensure that disposal takes place after checking with a monitor. Bags of waste must be removed from the Radiation Room to the Radiation Waste Store by the generator of the waste.

WASTE MUST BE REMOVED FROM THE RADIATION ROOM IMMEDIATELY ON COMPLETION OF THE PROCEDURE UNLESS STORAGE FOR DECAY HAS BEEN ARRANGED.

KEY TO THE RADIOACTIVE WASTE STORAGE SHED (“BUNKER”) ON THE CALLAGHAN CAMPUS CAN BE OBTAINED FROM THE UNIVERSITY RADIATION SAFETY OFFICER OR THE SECRETARY, SCHOOL OF BIOLOGICAL SCIENCES.

All material deposited in the BUNKER must be noted on the register in the shed. If it is removed at a later date for disposal then this fact should be noted next to the entry in the Register and a line marked through the entry.

6.9 DISPOSAL LIMITS
There are two sets of guidelines for disposal of radioactive waste. The statutory guidelines in NSW are laid down in the Regulations (2003) to the NSW Radiation Control Act 1990. There is also the "Environmental Guidelines: Assessment, Classification & Management of Liquid and Non-liquid Wastes (1999)". Both of these provide guidelines for the discharge of any particular radionuclide.

Under the NSW regulations, if there is more than one radionuclide present at any one time, the sum of the quotients (concentration/maximum permissible concentration) for all radionuclides present shall not exceed one as indicated in 6.1 above. This is obviously a difficult calculation to work to and a number of assumptions must be made as to the actual number of radionuclides present and their relative concentrations. However the calculations must be done and recorded.