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Section 7: Waste Disposal


A. Acceptable Containers

  • A 2.5 gallon linear polyethylene carboy for used liquid radioactive materials is recommended because of its portability, ease of storage, and resistance to corrosion.

B. Segregation of Liquid Waste

  • Liquid radioactive materials will be collected in separate containers as follows:

    1. Aqueous materials containing long half-lived isotopes
      • Use this container for aqueous materials only.
      • No organic solvents or hazardous chemical shall be placed in this container.
      • No solids or any materials which are insoluble in water shall be placed in this container.
      • No materials too viscous to pass through a 20 mesh sieve shall be placed in this container.

    2. Aqueous materials containing short half-lived isotopes
      • Use this container for aqueous materials only.
      • No organic solvents or hazardous chemicals shall be placed in this container.
      • No solids or any materials which are insoluble in water shall be placed in the container.
      • No materials too viscous to pass through a 20-mesh sieve shall be placed in this container.

    3. Biodegradable liquid scintillation fluid containing long half-lived isotopes other than H-3 and C-14 only
      • No organic solvents shall be placed in this container.
      • No solution containing more than .05 microcuries per gram may be placed in this container.
      • No materials too viscous to pass through a 20-mesh sieve shall be placed in this container.

    4. Biodegradable liquid scintillation fluid containing H-3 and C-14 only
      • No organic solvents shall be placed in this container.
      • The addition of any other radioactive materials to this container will prevent its proper disposal.
      • No solution containing more than .05 microcuries per gram may be placed in this container.
      • No materials too viscous to pass through a 20-mesh sieve shall be placed in this container.

    5. Biodegradable liquid scintillation fluid containing short lived isotopes
      • This material will be held for decay prior to disposal if the half-life is less than 90 days.
      • Only liquid scintillation fluid utilized as counting solution for short lived isotopes shall be placed in this container.
      • Non-biodegradable liquid scintillation fluid containing long half-lived isotopes other than H-3 and C-14 only
      • No organic solvents other than those used as counting solution shall be placed in this container.
      • No solution containing more than .05 microcuries per gram may be placed in this container.
      • No materials too viscous to pass though a 20-mesh sieve shall be placed in this container.

    6. Non-biodegradable liquid scintillation fluid containing H-3 and C-14 only
      • No organic solvents other than those used as counting solutions for H-3 and C-14 labeled substances shall be placed in this container.
      • The addition of any other radioactive materials to this container will prevent its proper disposal.
      • No solution containing more than 0.5 microcuries per gram may be placed in this container.
      • No materials too viscous to pass through a 20-mesh sieve shall be placed in this container.

    7. Non-biodegradable liquid scintillation fluid containing short lived (T1/2~<90 days) isotopes
      • These materials will be held for decay prior to disposal if the half-life is less than 90 days.
      • Only liquid scintillation fluid utilized as counting solution for short lived (T1/2<90 days) isotopes shall be placed in this container.

    8. Organic solvents other than liquid scintillation fluid containing long half-lived isotopes (T1/2>90 days) shall be placed in a separate container.
    9. Organic solvents other than liquid scintillation fluid containing short half-lived isotopes (T1/2<90 days) shall be placed in a separate container.

C. Rules Regarding Liquid Scintillation Fluids, Vials, and Caps

  • Revised 6/19/13: Liquid scintillation vials containing counting solution with carbon-14 and/or tritium should be placed in a zip-lock bag for radioactive material disposal.

D. Rinsing of Liquid Scintillation Vials for Disposal in Regular Trash

  • Revised 6/19/13: Liquid scintillation vials containing radioactive materials other than carbon-14 and/or tritium should be placed in a separate zip-lock bag for radioactive material disposal.

E. Liquid Waste Pickup

  • All liquid radioactive materials will be analyzed for content and activity upon pick-up. Any improperly packaged or labeled containers will be returned to the Authorized User for repackaging. Carboys will be recycled to the Principal Investigator when the contents have been properly disposed. This procedure may take some time and one should be aware that additional carboys may need to be purchased occasionally.

F. Used Radioactive Materials Designation Statement

  • Revised 6/19/13: Used radioactive materials are collected by Baylor University EHS Department. Used radioactive materials are not officially designated as waste until they have been received and classified. Channels of disposal include storage for decay, minute amounts disposed via sewer, and shipment to a commercial disposal site.

G. Collection Procedures for Used Radioactive Materials

  1. General Requirements
    • Each container must have a current Consolidated Radioactive Materials sheet available, either attached to the container or at a nearby location. (A clipboard hanging in a readily accessible spot is acceptable.)
      • The top general information portion of the Consolidated Radioactive Materials sheet must be filled out when the container is placed in use.
      • The sheet must be completely filled out before time for pickup of the container.
      • It is recommended that the data be added to the sheet each time that a disposal is made rather than estimated when the container is full.
      • Total the amount of each isotope and record this information at the bottom of the sheet.
      • Do not overfill carboys. The liquid level must be at least 1 inch below the top of the carboy.
      • Do not place viscous materials in a carboy. The material must pass readily through a 20-mesh sieve.

    • Each consolidated materials container must have a radiation warning symbol attached.
    • Long and short lived radioactive materials must be collected in separate dry materials drums. Carbon-14 and tritium are long lived. Isotopes with half-lives less than 90 days are short lived. Contact the Radiation Safety Officer about materials which do not fall in either of these classes. Replacement drums will be furnished by the Radiation Safety Officer when available, as drums are emptied for compaction, or after storage for decay. It may occasionally be necessary for a researcher to buy a replacement drum.

  2. Dry Solid Materials
    • Place all dry solid materials in an approved 30 gallon drum marked "DRY SOLID MATERIAL ONLY." This drum must be lined with a bag of at least 6 mil thickness. Small amounts of water containing non-volatile radioactive materials may be absorbed on paper in these drums. However, no liquid of any kind can be accepted. The presence of one small vial containing a milliliter of solution may result in the entire drum being refused at the disposal site! Empty glassware, excluding liquid scintillation vials, may be disposed of as dry solids. No liquid scintillation vials or caps may be placed in this container! If the drum is found to have an exposure rate of greater than 0.5mR/hr at any point on the surface of the container, a shipping form (available from the Radiation Safety Officer) must be filled out and attached to the drum along with the Consolidated Radioactive Materials sheet. All radioactive materials labels must be defaced or removed before placing any object into the solid waste container.

  3. Sharp Objects
    • Hypodermics, broken glass, and other sharp objects must be packaged to avoid injury to persons who must handle the waste. Place such objects in a plastic jar or metal container and secure with tape before placing them with the solid materials. Do not use "RADIOACTIVE MATERIALS" tape to secure the container before it is placed in the solid materials container.

  4. Uncontaminated Materials
    • Do not place uncontaminated materials in the used radioactive container. Packing, boxes, and other such materials, when not contaminated, should be placed in the non-radioactive waste can for disposal at the city landfill.

  5. Animal Carcasses and Animal By-Products
    • Contact the Radiation Safety Officer for special packaging instructions before conducting any experiment which will produce animal carcasses or by-product.

  6. When Materials are Ready for Pickup
    • Make sure that the consolidated materials sheet contains all required information.
    • Make sure that a completed shipping paper is attached to any solid drum that has a measured surface exposure rate exceeding 0.5mR/hr or of any container with an activity that exceeds limited quantity activities.
    • Contact the Radiation Safety Office. Specify the type of material and size of container.
      • Improperly packaged materials will not be picked up.

H. Sewer Disposal by Authorized Users

  • No radioactive materials may be disposed of by sewer without specific approval. In case such disposal is approved, records must be maintained listing isotope, amount, and date of disposal.

I. Mixed Waste

  • Mixed waste is waste which contains hazardous chemicals in addition to radioactive material. Both the chemical and the radiation hazard must be considered in the disposal of this waste. Sometimes the hazardous chemical can be neutralized or otherwise rendered harmless so that the material can be disposed of as radioactive waste. Sometimes the radioactive material can be held for decay and the chemical then disposed of as a hazardous chemical.

  • If the radioactive material is long lived and the chemical not easily rendered harmless, a commercial waste disposal company must be found to dispose of the waste. The cost for disposal may be excessive. For some types of hazardous chemicals and radioactive materials mixtures, there are no approved methods of disposal.
  • Examples of hazardous waste that present severe disposal problems are the following:

    1. Solvents containing chlorine, sulfur, or nitrogen and a long lived radioactive material. These materials cannot be incinerated in most incineration systems. While some organic materials, such as toluene, can sometimes be incinerated, they often need to be held for long periods of radioactive decay before incineration. This may be a violation of federal regulations on storage of hazardous materials.
    2. Aqueous or organic solutions containing pesticides or other hazardous chemicals and long lived radioactive materials. All university faculty members are urged to avoid producing mixed waste when possible. The use of biodegradable liquid scintillation fluids can greatly reduce the quantity of mixed waste, since the biodegradable solutions do not contain substantial quantities of hazardous chemicals.

J. Supplemental Information on Disposal of Waste

  1. General Information
    • Used radioactive materials are designated as waste only after being collected, analyzed, if necessary, classified, and designated for specific methods of disposal. Some may be recycled.
    • All used radioactive materials must be collected in approved containers. Typically, solid materials are collected in 30 gallon fiber drums and liquids are collected in 2.5 gallon carboys.
    • A standard waste disposal sheet must be displayed on each container offered for disposal.
      • Display the disposal sheet open on the side of the carboy or the top of the drum. Do not fold.
      • Fill out all required information.
      • Write legibly. Use units specified at the top of the column.
      • Record all totals before offering the container for disposal.

    • Do not place any liquids in dry waste drums or any solids in liquid carboys.
    • The AU faculty member is responsible for all radioactive materials until pickup.

  2. Collection of Liquid Waste
    • Do not place any solid materials in liquid waste carboys. Filter papers, glass objects, and plant materials are prohibited. Materials too viscous to pour readily through a 20-mesh sieve cannot be accepted. Precipitates must be filtered out.
    • Do not overfill carboys. The liquid level should be approximately 1 inch below the top of the carboy. Most carboys have a 2.5 gallon mark. Carboys may be filled to this point.
    • Viable bacteria, yeast, or other biological materials are not permitted. Clorox or other appropriate material may be added to aqueous carboys to insure that no active microorganisms are present. Do not add over 10% Clorox.
    • Isotopes with half-lives greater than 90 days should not be mixed with isotopes having half-lives less than 90 days.
    • Carboys may be returned to the AU faculty member after disposal of waste. Since carboys may have to be held for decay or for scheduling of disposal by sewer or incineration, extra carboys should be purchased by the researcher if his/her supply is exhausted.
    • All material in aqueous carboys must be miscible with water. No layering is permitted.
    • Liquid scintillation fluid containing carbon-14 and/or tritium should be collected separately from other radioisotopes. Liquid scintillation fluid should contain no more than 0.05 microcurie per gram of carbon-14 and tritium combined.
    • Liquid scintillation fluid carboys should contain only counting samples and organic wash solution used to rinse counting vials. High level activity such as that from stock bottles cannot be disposed as liquid scintillation fluid.
    • Revised 6/19/13: No liquid scintillation vials or caps are permitted in solid waste drums.
    • Revised 6/19/13: The use of non-biodegradable liquid scintillation fluids is not recommended.
    • Revised 6/19/13: Organic liquids other than liquid scintillation fluid should be collected in a separate carboy for pickup. Small amounts of organic compounds which are included in liquid scintillation samples or used to rinse out scintillation vials may be included in liquid scintillation carboys for incineration.

  3. Disposal by Sewer
    • State regulations permit the disposal of small amounts of liquid containing radioactive materials by sewer, provided specific requirements are met.
    • There are limits for both quantity and concentration which vary for different isotopes.
    • In order that university researchers do not violate any regulations concerning sewer disposal, consult with the Radiation Safety Officer. (Revised 6/19/13)

  4. Collection of Solid Waste
    • Solid radioactive waste must be collected in an approved container. A 6 mil plastic liner must be used.
    • Each researcher should keep an adequate supply of drums on hand. Empty drums will be returned to laboratories when available.
    • Drums will be held until the waste material is emptied. Long lived waste (half-life greater than 90 days) will be compacted for shipment to a commercial site. Short lived waste will be held for decay for 10 half-lives, then disposed of as non-radioactive waste.
    • When no empty drums are available, the researcher will be responsible for procurement of more drums as needed. If the name of the researcher is written on the drum, the drum may be returned to his/her lab when empty.
    • Empty drums will not be stored. If the faculty member who purchased the drum does not want it back when empty, the drum will be issued to a laboratory where an empty drum is needed.
    • Under no circumstances should liquid scintillation vials or caps be placed in a dry waste drum.
    • Sharp objects such as broken glass, Pasteur pipettes, and hypodermic needles must be secured in a box or metal container before being placed in a drum. Combustible waste (paper, plastic, rubber gloves) may be placed directly into the drum.
    • Long lived waste (half-life greater than 90 days) must be collected in a separate drum from short lived (half-life less than 90 days) waste.
    • Slightly damp paper can be placed in solid waste drums. No free running water can be accepted either inside containers or as wet objects in the drum. Glass, plastic, or other materials containing visible water droplets must be dried before being placed in the waste drum. Mud and wet plant materials are prohibited.
    • Paper or other materials that do not have detectable activity should not be disposed of as radioactive waste. This material should be disposed of as ordinary trash. Examples of this type of material are radioactive shipping containers and bench-cote which contain no detectable activity. Glassware and plastic ware may also often be disposed of as ordinary trash. Only materials with detectable activity should be disposed of as radioactive waste.
    • Deleted 6/19/13, repeat information.
    • Washes should be collected and evaluated for waste status.
    • Contaminated dust which can become airborne must be sealed in a separate plastic bag inside the solid waste drum. Examples of this type of material include dust, sawdust, powders, and dry plant materials.
    • All radioactive materials stickers must be defaced or removed before being put into the solid waste drum.