Low-level radioactive waste (LLRW) is generated at UNM in the course of conducting regulated activities with radioactive material (RAM). LLRW must be properly collected and segregated according to its physical form, radionuclide half-life, and chemical characteristics to facilitate final disposal and protect people and the environment from excessive exposure to ionizing radiation. Please refer to the specific requirements and unique characteristics of the different categories of waste below and contact the Office of Radiation Safety for more information about generating LLRW at UNM.
Aqueous Liquid Waste denotes any waste of which the primary solution is water and any soluble organic and inorganic constituents, all present in quantities and forms that do not result in phase separation or precipitation.
Care must be taken to make sure that the quantities of organic or inorganic components added to the water do not make the mixture a mixed waste. Even small amounts of substances, when combined with nonhazardous materials, may result in a mixed waste. A solution containing as little as 6% methanol in water is a mixed waste.
Consult with the Office of Radiation Safety before adding any organic material to aqueous waste. Aqueous liquid waste will normally consist of aqueous phase extractions from experiments and the first rinsing of radioactive material containers.
Biological waste primarily consists of animal carcasses, bedding, and excrement. It may also include specimens in vials or containers. Waste containing biological (excluding animal carcasses), pathogenic, or infectious material or equipment (e.g., syringes, test tubes, capillary tubes) used to handle such material, shall be treated to reduce, to the maximum extent practicable, the potential hazard from the non-radiological materials.
Waste with a half-life less than 90 days needs to be segregated from other waste. Small animals may be bagged and kept frozen until the date of pick-up. Researchers working with large animals such as large dogs, sheep, or hogs must contact the Office of Radiation Safety to make arrangements for disposal.
Liquid Scintillation Waste is liquid waste, which usually consists of a xylene or toluene based scintillation fluid. LS waste is divided into two categories based on the radionuclides present and the average activity per gram of media: (1) H-3 and C-14 waste with an average activity of less than 0.05 uCi per gram of media, and (2) all other radionuclide LS waste.
Estimates of activity should be based on calculations from actual vial counting. An average of 0.05 uCi per gram of media amounts to about 250 microcuries per case of standard 20 millimeter 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, LSV waste activities that exceed 100 microcuries per case of standard vials, or a 5 gallon can of waste.
It is important to have a realistic assessment of activity in these wastes. Most LS waste will be generated in vial form. Special arrangements need to be made with the UNM Radiation Safety Office for LS waste that is not collected in vial form.
Mixed Waste contains radioactive material and one or more hazardous chemical components. Most chemicals classified by the EPA as hazardous are disposed of under the Resource Conservation and Recovery Act (RCRA). The hazardous waste can be either a listed hazardous waste in SubPart D of 40 CFR 261 or a waste that exhibits any of the hazardous waste characteristics identified in Subpart C of 40 CFR Part 261.
Hazardous waste contractors will not accept a hazardous waste that contains radioactive material. Due to the expense and difficulty of disposal, generating mixed waste is specifically PROHIBITED unless approved in advance in writing by the Radiation Safety Officer (RSO).
Solid Dry Waste normally consists of absorbent pads, gloves, disposable labware, pipettes and other similar items contaminated with radioactive material. Solid dry waste must not contain liquids, sharps, lead pigs, scintillation vials (even empty vials), chemicals, or biologicals. Waste will be segregated by half-life: < 30 days, >30 to 60 days, >60 to 90 days, >90 days, and transuranics.
If more than one waste category exists in a laboratory, the waste containers will be marked as to which radionuclides are to be placed into each specific container. Compliance with such markings is essential. Careful consideration should be given to external dose rates created by gamma and high energy beta emitters placed into waste storage containers. It may be necessary to shield the material or make arrangements with the Office of Radiation Safety for immediate pick-up.
The presence of high concentrations of chelating agents in the radwaste may have an effect on waste-site stability. All waste containing chelating agents 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 polycarboxlic acids (e.g., EDTA, DTPA) and hydroxy-carboxylic acids (e.g., citric acid and glucinic acid) used for the purpose of binding (i.e. to stabilize radioactive materials).
Uranyl/Thorium Compounds, Staining Solutions, Dry Uranyl Acetate, Uranyl Nitrate, Thorium Nitrate and solutions containing concentration of these shall be collected and disposed of as radioactive waste. Never combine waste containing uranyl or thorium compounds with any other chemical waste, such as lead citrate.
All waste generated must have recorded with it the total number of grams of uranyl or thorium compounds.
Office of Radiation Safety
MSC 08 4560
1 University of New Mexico
Albuquerque, NM 87131
Physical Location:
RHFH (Fitz Hall) - Room B89
Phone: 505-925-0743