Radioactive Waste Disposal Guidelines
TABLE OF CONTENTS
- Traditional Fluids
- Biodegradable and Nontoxic Fluids
- Approved Disposal Methods for Traditional Fluids
- Approved Disposal Methods for Biodegradable and Nontoxic Fluids
- Approved Fluids for Sink Disposal
- Excluded Materials
The Radiation Safety Section provides containers for the disposal of dry solid radioactive waste to all radionuclide projects using unsealed radioactive material. The container consists of a 23 gallon plastic Rubbermaid base with a plastic liner and lid. The base and lid are labeled with radiation warning signs and other important information. Separate containers are provided for short-lived (half-lives of 90 days or less) and long-lived radioactive waste (half-lives greater than 90 days). The plastic bags that line the containers and the labels on the container and lid are color coded green for short-lived waste and yellow for long-lived waste.
Small bench top containers may also be used for the collection of dry solid radioactive waste provided the following precautions are taken:
- The container is properly labeled with the universal radiation warning symbol and the words "Caution, Radioactive Material." The color of the symbol and words may be magenta, purple, or black on a yellow background. In addition a work area sign (available from the Radiation Safety Section) should be posted in the area.
- Waste should be removed from these smaller containers frequently. If waste is allowed to accumulate, a separate radioactive waste log should be maintained.
The dry solid radioactive waste container is made of 1/8 inch thick linear low density polyethylene, which has a density of about 0.9 grams per cubic centimeter. It is thick enough to stop beta particles below about 600 keV including those from C-14, S-35, and Ca-45. Some of the more energetic beta particles from P-32 will penetrate the container, but will emerge with a reduced energy. If needed, a properly sized waste container beta shield is available from Nalgene dealers. A photograph of the shield is provided below. Contact your favorite Nalgene dealer (e.g., Fischer Scientific) for pricing information.
Nalgene 6745-9024 waste container shield.
Each disposal of radioactive waste must be entered on the log form provided by the Radiation Safety Section, and entries must be reasonably accurate. Disposal information must be summarized and reported on the Monthly Radionuclide Inventory Reports.
The following items may never be placed in a dry solid radioactive waste container:
- Radioactive warning labels (Refer to the Section 5.6.5 of UIC Radiation Safety Manual).
- Sealed sources and check sources
- Uranium and thorium compounds
- Hypodermic needles and syringes
- Biohazardous or chemically hazardous radioactive waste
- Nonradioactive waste
- Biohazard bags
- Liquids including scintillation fluid and HPLC solvents
- Gaseous radioactive material
- Animals (see additional information below)
LIQUID RADIOACTIVE WASTE
Low level liquid radioactive waste may be poured down approved laboratory sinks if all of the following requirements are satisfied:
- The waste is readily soluble or miscible in water, or must be biological material that is readily dispersible in water. Waste containing radioactive microspheres may not be disposed of by sink because they accumulate in traps and low points in the sewage system.
- The waste may not contain chemical compounds or biohazardous materials that are not permitted to be poured into sinks. Some scintillation fluids may be disposed of by sink.
- Disposals must be made in sinks that are posted by the Radiation Safety Section with yellow and magenta sink disposal signs. The instructions printed on the sign must be followed.
- The total activity disposed of in any calendar month must not exceed the limit stated in the project authorization documents, usually 3 mCi per month of all radionuclides combined.
- Reasonable precautions must be taken to prevent the sink from becoming contaminated. A funnel and plastic tubing supported by a ring stand may be used to direct the contaminated liquid directly into the drain. The sink should be flushed with copious amounts of running water during and immediately after the disposal.
- The sink must be surveyed for contamination after each disposal and decontamination must be performed whenever contamination is detected.
- A reasonably accurate record must be made promptly after each disposal on the disposal log provide by the Radiation Safety Section.
- Disposals must be summarized and reported on the monthly Radionuclide Inventory Report.
The following radioactive liquids may not be discharged into the sewer system:
- Material that is prohibited from being sewage disposal by any regulation. Call the Health and Safety Section at extension 6-7233 (6-SAFE) for additional information.
- Material that is not soluble or biological material that is not readily dispersible in water.
- Any waste that contains radioactive microspheres.
- Any waste that would cause the maximum permissible monthly disposal limit for the project to be exceeded.
LIQUID SCINTILLATION WASTE
Liquid scintillation fluids (cocktails) can be broadly categorized by the solvents they contain.
Traditional fluids contain toluene, xylene, pseudocumene, and other low flash point hydrocarbon solvents that are categorized as flammable liquids. Most of these solvents are also recognized by the EPA as hazardous for the purpose of waste disposal. They evaporate readily and can cause fire, explosion, and inhalation hazards. Traditional scintillation fluids may NOT be disposed of by sewer, but must be disposed of by transferring them to the Radiation Safety Section. While their use is not prohibited, it is discouraged.
Some of the newer scintillation fluids contain solvents such as DIN (di-isopropylnaphthalene), PXE (1-phenyl-1-xylylethane), and LAB (linear dodecyl benzene or linear alkylbenzene). These solvents have higher flash points, which reduces the potential for causing fires and explosions. They are also safer for laboratory personnel to handle because they have much lower toxicity. Because most of these fluids are biodegradable and are not categorized as hazardous by the EPA, sewage disposal is allowed. Use of these types of scintillation fluids, and subsequent sewage disposal, is encouraged.
Traditional fluids must be disposed of as hazardous waste. The Radiation Safety Section will collect scintillation vials and bulk fluids after they are properly categorized and packaged. Packaging instructions are found on the scintillation waste disposal form.
A large number of scintillation fluids that are marketed by the manufacturers as biodegradable or nontoxic were evaluated by the EHSO's Radiation Safety Section and the Health and Safety Section. Fluids that meet the following criteria may be poured directly down approved laboratory sinks.
Sink Disposal Criteria
- The fluid must be approved by the Radiation Safety Section for sink disposal (see list below).
- The material may not contain any hazardous waste that could not be disposed of via sewer (refer such questions to the Health and Safety Section at extension 6-7233).
- The pH of the fluid must be between 6 and 9.
- The fluid will not gel inside the drain pipe during or after disposal.
- The disposals will not exceed the sewage disposal limit established for the project (usually 3 mCi/month of all radionuclides combined, but check project authorization documents for the official project limit).
Sink Disposal Instructions
- Be sure the scintillation fluid meets the sink disposal criteria (above).
- Make disposals only in sinks that are approved for disposal of liquid radioactive waste (posted by the Radiation Safety Section).
- Wear disposable laboratory gloves and a lab coat.
- Turn on the water to a moderate flow rate.
- Slowly pour the scintillation fluid directly down the drain hole of the sink. It may be useful to pour the liquid into the drain using a a funnel with plastic tubing supported by a ring stand. Make sure the tubing is inserted at least 6 inches into the sink drain.
- Thoroughly rinse each emptied vial with water and drain any residual liquid from the vials. More thorough decontamination is recommended if vials will be recycled.
- If a funnel and tubing is used for disposals, rinse them thoroughly when done.
- Let the water flow for at least 5 minutes after the disposal. Do not leave sinks with running water unattended.
- Make a reasonably accurate entry on the sewage disposal log form by the sink and record the disposal on the next inventory report in the sewage disposal column.
- If the vials will be discarded as waste, vials that contained H-3 and C-14 in concentrations of less than 0.05 microcurie per milliliter have been deregulated by the IDNS and may be disposed of as ordinary trash. Vials that contained other radionuclides or that contained H-3 or C-14 in excess of 0.05 microcurie per milliliter must be placed in a radioactive waste disposal container. Enter a nominal value of 0.01 microcurie of the appropriate radionuclide(s) on the solid waste disposal log for every 100 vials placed in the container.
The following fluids were evaluated and are approved for sink disposal at UIC.
The following liquids may NOT be included with scintillation waste.
- Concentrated Solutions and Stock Solutions - Concentrated solutions, such as material from stock bottles, may not be put into scintillation vials or included with trays of vials for disposal as scintillation waste.
- Nonaqueous Solvents - Contaminated solvents that cannot be disposed of by sink may not be disposed of as scintillation waste.
- Nonradioactive Liquids - Nonradioactive liquids, including uncontaminated scintillation fluids, may not be disposed of as scintillation waste. Contact the Health and Safety Section for disposal of all nonradioactive hazardous liquids.
Animal Waste that is contaminated with radioactive material should be placed in opaque plastic bags and kept frozen until collected by Radiation Safety Section. Each bag should be labeled with the radionuclide, activity, and date. Never put animal waste, tissue samples, or objects contaminated with blood, urine, or feces into dry solid waste containers. Chapter 5, Section 5.10, of UIC Radiation Safety Manual contains additional information. Projects that are authorized to use radioactive material in animals have detailed instruction for waste disposal in their project authorization documents.