Northwestern Office for Research


22.0 Radioactive Waste

Note: The following is excerpted from the full Radiation Safety Handbook

General Responsibilities

The generation, regulation, and disposal of radioactive waste are among radiation workers’ most important activities. Generation involves much more than simply creating contaminated material; it also involves controlling the composition and volume as well as paying attention to chemical, biological, and radiation safety and record keeping. Regulation involves complying with the evolving requirements of the University, governmental agencies, waste brokers, and waste-site operators. Disposal involves handling of the wastes by many individuals and businesses in the chain of custody from the generator to the disposal site.

The generator has cradle-to-grave responsibility for hazardous wastes, a responsibility that never can be relinquished. There are institutional, civil, and criminal penalties for failure to fulfill generator's obligations, so you must exercise positive control over what you place in radwaste containers and associated records. Disposal of any radioactive material except by ORS is prohibited without express prior consent of ORS.

Reducing Non-Radiological Hazards

Illinois regulations state, "Waste containing hazardous, biological, pathogenic, or infectious material shall be treated to reduce to the maximum extent practicable the potential hazard from the non-radiological materials." The goal is twofold: to minimize the potential hazards to those persons handling the waste at each step of the disposal process, and to minimize the potential impact on the biosphere.

Reducing Biological Hazards

The authorized investigator shall ensure that radioactive waste containing hazardous biological, pathogenic, or infectious material is treated to reduce the hazard from non-radiological materials to the maximum extent practicable. Potentially infectious material shall be chemically disinfected or autoclaved prior to placing it into radioactive waste containers. Liquid waste shall be treated to prevent or inhibit biological growth. Autoclaving is generally not recommended for radioactive wastes because of the potential for contaminating equipment and generating radioactive vapors. Contact ORS before generating mixed infectious/radioactive waste for guidance in its handling.

Reducing Physical Hazards

Radioactive waste shall be treated to reduce to the maximum extent practicable the physical hazards from needles, broken glass, and other sharp objects. Needles and other sharp objects shall be collected only in appropriate sharps containers and shall not be placed loose into radioactive waste containers.

Reducing Chemical Hazards

Radioactive waste shall be treated to reduce chemical hazards to the maximum extent practicable. ORS strongly encourages you to use experimental protocols that do not generate mixed chemical and radioactive waste. Carcinogens, reproductive toxins, and other highly toxic materials shall be treated to reduce their hazards to the maximum extent practicable. However, be aware that EPA restrictions on treatment in the laboratory may severely limit your options. Neutralizing inorganic acids is one of the few approved treatments. Contact ORS for approved treatment procedures. Extraordinary costs related to disposal of mixed waste may be charged back to the user.

Radiation Protection

Radioactive waste containers may be significant sources of contamination and external dose. Authorized investigators shall take appropriate steps to ensure that the collection and storage of radioactive waste is performed safely and in accordance with all applicable policies and procedures.

These guidelines will help reduce the hazards from your radioactive wastes:

  • Use the strategies of time, distance, and shielding. Keep radwaste containers close to the radiation work area and away from desks and other frequently occupied areas. Shield wastes just as you would shield your stock materials: use high-density shields for gamma emitters and plastic shields for beta emitters. Shield bench-top waste collection containers.
  • Control volatility. Airborne radioactive material may be a problem with radioiodine, sulfur-labeled amino acids, metabolic products in animal experiments, liquid scintillation media, and other wastes. Control volatility in liquid radioiodine wastes by adding a solution of 0.1 M sodium hydroxide, 0.1 M sodium iodide, and 0.1 M sodium thiosulfate. Collect dry wastes with volatile components in tightly sealed plastic bags before putting them into radwaste drums. Keep all containers tightly closed. If wastes are stored in fume hoods, keep the waste in the rear of the hood, in small containers. Do not freeze sodium iodide, because the evolution of volatile components may increase when it is thawed. Do not store volatile wastes in laminar flow cabinets or biological safety cabinets or any location where potentially contaminated air is recirculated into the room. Store liquid scintillation media in a well-ventilated area.
  • Control contamination. Protect work surfaces under waste containers. Do not invert lids on dry waste containers. Do not set equipment on top of waste containers. Securely bag dry waste being carried to the dry-waste container. Use secondary containers when carrying liquid wastes to the waste container. Do not overfill containers. Use a funnel with liquid wastes. Use protective gloves every time containers are handled. Perform routine contamination checks. Use strong, leak proof plastic bags for animal carcasses.
  • Control contaminated sharps. Needles and other sharps contaminated with radioactive material shall be collected in puncture-resistant containers. Needles and needles attached to syringes (even if they are capped) shall not be placed loose in radioactive waste containers. To prevent puncture wounds from contaminated needles, recap or remove them only when no alternative is feasible. Any recapping or removal should be accomplished through the use of a mechanical device or a one-handed technique.
  • Use protective clothing and equipment. Always wear lab coats, gloves, and eye protection when handling radioactive waste.
  • Wear your dosimeter. If you were issued a dosimeter, use it when handling radioactive waste.
  • Incident reports. Report all spills and injuries that occur when handling radwaste.

Radwaste Record Keeping

Authorized users and radiation workers shall maintain written records of activity for each radionuclide consigned to waste. These records should be decay-corrected. You should be able to account for all activity in your inventory. ORS reviews records of radionuclide use and performs independent analysis of radionuclides in waste containers to ensure that record keeping is accurate. Wastes that do not conform to record-keeping requirements may not be accepted for disposal. The following form is used for radionuclide record keeping:

Radionuclide Inventory Form. ORS issues the Radionuclide Inventory form for each shipment of radioactive material to the laboratory. Radiation workers shall use it to record activity disposed as waste. Accurate record keeping on this form will help you estimate activity in waste containers. Keep records of activity in uCi or mCi or their SI equivalents (Becquerels).

Investigators shall maintain a written record of the waste placed into each container. It could be a separate log, however the information shall be available at all times and shall be transcribed onto the on-line pickup request.

Uranyl Acetate and Staining Solutions

Uranyl acetate should be collected and disposed of as radioactive waste. Never combine uranyl acetate with any other chemical waste, such as lead citrate.

Chelating Agents

The presence of high concentrations of chelating agents in the radwaste may have an effect on waste-site stability. The online waste pick-up request shall indicate the name and weight percentage of any chelating agents that are present in excess of 0.1% by weight. Chelating agents are amine polycarboxylic acids (e.g., EDTA, DTPA) and hydroxy-carboxylic acids (e.g., citric acid, carbolic acid, and glucinic acid) used for the purpose of binding (i.e., to stabilize radioactive materials).

Mixed Wastes

Intentional generation of a mixed waste without advance permission from ORS is prohibited. A mixed waste contains radioactive material and at least one hazardous chemical component. Most chemicals classified by the EPA as hazardous under the Resource Conservation and Recovery Act (RCRA) may not be released to water, air, or landfill. Hazardous waste contractors will not accept radioactive material. There are few, if any, disposal options for many mixed wastes.

To avoid conflicts between regulatory requirements and prudent safety and health practices, avoid generation of mixed radioactive and RCRA hazardous waste. Prevent cross-contamination of radioactive and non-radioactive components. Substitute non-radioactive materials or non-hazardous chemicals in your processes. Do not place lead pigs, other elemental lead or lead-containing materials into radioactive waste containers.

Biohazard Bags

The use of bags bearing the word "biohazard" or the international biohazard symbol for the collection of radioactive waste is prohibited. For legal reasons and for the protection of waste handlers, these two waste streams may not be mixed. As previously stated, mixed biohazardous and radioactive waste must be treated to reduce the non-radiological hazard to the maximum extent practicable. After this is done, the material is no longer biohazardous and the biohazard bag is no longer appropriate. Bags that once contained mixed biohazardous and radioactive waste that has been autoclaved should be over-bagged with an opaque bag before being placed in radioactive waste containers.

Radwaste Labels

Each container of radioactive waste shall bear a label or tag identifying the contents at all times; identifying the nuclide in the container is essential. All labels, tags, tape, stickers and markings that indicate the presence of radioactive material or bear the radiation warning symbol shall be removed or defaced before they are placed in radwaste containers.

Requests for Pickup

ORS picks up radioactive waste on request.  All requests for pickup must be made through the Northwestern Safety Information System (NSIS).  To initiate a request after logging into NSIS with your net ID and password, select Hazardous Waste Pickup Requests in the User Tools menu.  On the next screen, click the available link to Add New Waste Pickup Request.  Next click the radio button beside Radioactive Waste and the Next Screen to begin the wizard that will complete the radioactive waste pickup request.  Remember that requests to pick up compounds containing uranium or thorium must use the radioactive materials request process.

After you have completed the wizard you will see a summary page listing all of the recent requests you have made.  You may review the requests using the modify icon (notebook and pencil) or you can begin a new request to dispose of another container of waste in a different waste stream.  Once you are confident the request is complete, click the button that will send you to the submission page and submit the request to ORS.  We will make every attempt to respond to your request within two business days.

Radwaste Containers

ORS supplies a variety of standard radioactive waste containers at no charge. The standard containers shall be used for final disposal unless permission to use other containers has been granted by ORS. ORS attaches "caution, radioactive material" labels to each container which shall not be removed or defaced. These containers are recycled; please do not write on them or apply stickers or tape.

  • Dry-Waste Containers. Fiberboard containers are available in 10-gallon and 22-gallon sizes. These containers have metal tops with spring closures, plastic liners, and appropriate labels.
  • Liquid-Waste Containers. Plastic carboys are available in 1-gallon and 5-gallon sizes. Each carboy has appropriate labels.

Liquid Radioactive Waste

Separate handling is required for the two types of liquid radioactive wastes, aqueous and non-aqueous.

Aqueous Waste

Aqueous waste denotes any solution of which the primary constituent is water and any soluble organic and inorganic constituents, all present in quantities and forms that do not result in phase separation or precipitation. Depending on the quantity of organic or inorganic components, aqueous waste may also be defined as a mixed waste. Even small amounts of substances, when combined with non-hazardous materials, may result in mixed wastes. For example, a solution of 6% methanol in water is a mixed waste. Consult ORS before adding any organic material to aqueous wastes. Aqueous waste shall be collected separately from non-aqueous waste. The following guidelines apply:

  • No more than two radionuclides shall be collected in any one container. See Table 22.1.
  • The pH of aqueous wastes shall be adjusted as close to neutral as possible, and pH shall be within the range pH 5 to pH 9. Solutions should be buffered if necessary to maintain pH in the acceptable range. ORS personnel may check the pH before removing waste from the laboratory.
  • Wastes shall be treated to reduce the non-radiological hazards and inhibit bacterial growth.
  • Do not overfill containers. Leave at least three inches of space at the top of the container.
  • Records shall be maintained of radionuclides and activity in the waste. Activity concentration values are not acceptable.
  • Aqueous wastes containing I-125 should be neutral or basic, securely capped, and stored in a well-ventilated area. Adding a solution of 0.1M sodium hydroxide, 0.1M sodium iodide, or 0.1M sodium thiosulfate may control volatility in liquid radioiodine wastes.
Table 22.1 Acceptable Radionuclide Combinations in Liquid Radwaste
  H-3 C-14 P-32 P-33 S-35 Ca-45 Cr-51 Rb-86 I-125 I-131
H-3 X X X X X   X X   X
C-14 X X X X X   X X   X
P-32 X X X X X X X X X X
P-33 X X X X X   X X   X
S-35 X X X X X   X X   X
Ca-45     X     X   X   X
Cr-51 X X X X X   X X   X
Rb-86 X X X X X X X X X X
I-125     X         X X X
I-131 X X X X X X X X X X

Organic Liquid Wastes

Organic liquid waste is any solution of which the primary constituents are organic chemicals. They may contain water or other organic and inorganic constituents, in quantities and forms that do not result in precipitation. Examples of organic liquid radwaste are bulk liquid scintillation fluid, HPLC fluid, and chloroform. Organic liquid radwaste shall be collected separately from aqueous liquid radwaste.

  • Acceptable combinations of radionuclides. See Table 22.1 for acceptable combinations.
  • Chemical composition. The on-line pick-up request shall describe the chemical constituents of the waste as well as all other required information.
  • Flammable radioactive waste. Bulk flammable liquids shall be stored in approved flammable material storage cabinets or, if quantities are less than 10 gallons, in safety cans.
  • Hazard reduction. Organic liquid radwaste shall be treated to reduce to the maximum extent practicable the hazards from the non-radioactive components. The generator shall inform ORS of the presence of any hazardous, non-radioactive component.
  • Record keeping. Records shall be maintained of radionuclides and activity in the waste. Acceptable units of activity are total uCi or mCi or their SI equivalents (becquerels) in the container. Activity concentration values are not acceptable.
  • Do not overfill containers. Leave at least three inches of space at the top.
  • Control volatility. Organic wastes may give off vapors that are both chemical and radiation hazards. Securely cap containers and store them in well-ventilated areas. If wastes are stored in a fume hood, use small containers located in the rear of the hood.

Phase Separation and Precipitation

Investigators shall identify each phase chemically and radiologically if phase separation occurs. Investigators should also be aware that precipitates might contain significant amounts of radioactive material that cannot be identified by analysis of the liquid fraction. Liquid wastes containing precipitates may not be picked up for disposal until the investigator identifies the precipitate and the activity in the precipitate.

Dry Radioactive Waste

  • Acceptable radionuclide combinations. Only one radionuclide may be placed in any dry-waste container for P-32, P-33, S-35, Cr-51, I-125 and any other radionuclide with a half-life of less than 90 days.
  • No liquids allowed. No liquids of any kind shall be placed in dry-waste containers, with the exception of residual liquid in emptied vessels or equipment and very small quantities (such as one milliliter or less) in microfuge tubes and other small vessels.
  • Remove lead pigs. All lead shall be removed from dry waste and stored separately for pickup.
  • Remove labels. All labels, tags, signs, and stickers indicating the presence of radioactive material or bearing the radiation warning symbol shall be removed or defaced before waste is put into the container.
  • No loose needles or unprotected sharps allowed. Needles and other sharp objects shall be collected in puncture-resistant containers.
  • Treat waste to reduce non-radiological hazards. Waste potentially contaminated with pathogenic organisms shall be treated by autoclaving or chemical disinfection. Carcinogens, teratogens, other highly toxic materials, and physical hazards shall also be treated.
  • Record keeping. Records shall be maintained of radionuclides and activity in waste. Acceptable units of activity are uCi or mCi or their SI equivalents (becquerels).
  • Containers. Dry waste shall be collected in the standard fiberboard containers provided by ORS. Very small volumes of dry waste may be collected in strong, tightly sealed plastic bags, which in turn are placed in closed cardboard boxes. When standard containers are full, seal the plastic liner with a twist tie and replace and seal the metal top. Do not overfill containers.

Liquid Scintillation Vials/Bulk LSC Fluid

The use of biodegradable liquid scintillation media is strongly encouraged. Solvent-based liquid scintillation media are mixed wastes. The guidelines for collecting organic liquid radwaste apply to solvent-based LSC fluids that are collected in the laboratory in bulk. The following guidelines apply to LSC fluids that are collected in the original vials. All LSC waste shall be disposed of through ORS. Disposal of any radioactive material by generators is prohibited. This includes biodegradable LSC waste.

  • Vials containing H-3 and/or C-14 shall be segregated from other vials.
  • Return standard vials to their vial trays. Return mini-vials to original boxes. Ideally, vials should be kept vertical during collection and storage to avoid leakage. If vials are collected in plastic bags, the bags must be chemically compatible, strong enough to contain any leakage and securely tied. Ordinary trash bags are not adequate. Do not use biohazard bags. Bags of vials shall be placed in closed boxes for pickup. An appropriate "caution, radioactive material" tape, sticker, label, or marking must appear on the box or bag.
  • Vials shall not be combined with any other waste (e.g., gloves, stock vials, etc.)
  • Guard against spillage. Make sure vials are securely capped. Handle glass vials carefully to avoid breakage.
  • Minimize non-radiological hazards. The chief non-radiological hazard is evolution of solvent vapors. Make sure vials are securely capped, kept from breaking, and stored in well-ventilated areas in small quantities. Always wear protective clothing--gloves, lab coat, and protective eyewear--when working with LSC media.
  • Record keeping. Record keeping is one of the most important aspects of LSC waste disposal. LSC waste is a waste category for which the generator should be able to determine the activity with a high degree of confidence because all vials are analyzed in the laboratory.

LSC waste is divided into two waste streams based on the radionuclides present and the average activity per gram of media: H-3 and C-14 waste with an average activity of less than 0.05 uCi per gram of media; and all other LSC waste. Make estimates of activity based on calculations from actual vial counting or product yields, labeling efficiencies, analysis of aqueous wastes, fractionation of activity into different process streams and so on. The following sample calculation illustrates the standard method of determining the activity in a set of vials. Determine counting efficiency by counting a standard of known activity and similar composition and dividing counts per unit time (cpm) by activity of the standard (dpm).

Equation 22.1 Activity in LSC Vials
Total uCi =

(average cpm per vial)( total number of vials)
(counting efficiency) ( 2.22 x 106)


average net cpm per vial = 1,100 cpm
counting efficiency = 0.4 cpm/dpm (40%)
total number of vials = 500

(1,100 cpm) (500 vials)
(0.4 cpm/dpm) (2.22 x 106)

= 0.62 uCi

An average of 0.05 uCi per gram of media amounts to about 250 uCi per case of standard 20 milliliter vials (500 vials). It is very unlikely that activity concentrations this high are routinely used in normal laboratory procedures. Generators should be prepared to justify (with supporting calculations or printouts) LSC waste activity that exceeds 100 microcuries per case of standard vials, per bag or box of mini-vials, or per container of bulk LSC fluid. If activity exceeds 100 uCi of H-3 and/or C-14 and supporting documentation is not provided, ORS may request it. It is important to have a realistic assessment of activity in these wastes.

Biological Waste

Biological waste consists primarily of animal carcasses and animal bedding. It may also include specimens in vials or other containers.

  • Place carcasses and tissues in strong, tightly closed, leak proof plastic bags at the conclusion of the procedure.
  • Do not put non-biological material in these bags. Collect paper, plastic, foil, syringes, absorbent, and so forth separately as dry waste and treat it, if necessary, to reduce nonradiological (primarily pathogenic) hazards.
  • Freeze carcasses while awaiting pickup.
  • Collect contaminated bedding in strong, tightly closed, leak proof plastic bags, place in a dry-waste drum and add lime (available from ORS).
  • Record the radionuclide and the total amount of activity in the bag. The acceptable unit of activity is mCi.
  • Needles and other sharps shall not be placed in bags with animal carcasses.
  • Tissue samples shall be drained and consolidated and then collected in strong, tightly closed, leak-proof plastic bags. Freeze them while awaiting pickup. Do not dispose of tissue samples with LSC vials.
  • Eggs must be collected separately as biological waste.

Northwestern University   

Research Home  |

Office for Research - 633 Clark Street, Evanston, IL 60208-1108

The Office for Research promotes, facilitates, and enhances research at Northwestern University.

© 2016 Northwestern University

Northwestern Home | University Policy Statements