SECTION 15: Radioactive Waste Disposal

• Disposal Options
• Waste Collection and Storage in the Laboratory
• Decay-In-Storage Program
• Liquid Scintillation Wastes
• Off-Site Disposal of Long-Lived Solid Wastes
• Sanitary Storage System
• Mixed Wastes

There are strict requirements placed on each waste generator by federal, state and local authorities regarding waste form, waste packaging and the design and operation of waste storage facilities. The programs and procedures which are described below have been established to ensure that radioactive wastes generated at the University are stored and disposed of in compliance with all federal, state and local regulations.

Disposal Options (top)

Radioactive wastes generated at Princeton University may be disposed of through several avenues. The following options are more thoroughly described in paragraphs 15.C, 15.D, 15.E and 15.F.

1. Certain short-lived isotopes are disposed of through the centralized Decay-in-Storage (DIS) Program, operated by the Molecular Biology Department, for ultimate disposal as nonradioactive waste.
2. Certain liquid wastes may be disposed of through the sanitary sewer.
3. Liquid scintillation wastes are disposed of off-site through a contracted radioactive waste disposal services broker.
4. Solid wastes contaminated with radionuclides with half-lives greater than 90 days are disposed of off-site through a contracted radioactive waste disposal services broker.
5. Regardless of the disposal option used, specific departmental arrangements for the disposal and collection of radioactive waste vary and should be carefully checked with the "Departmental Safety Manager" and/or the departmental waste manager. All steps in the procedures, including selection of a waste container, designation of the container for a particular type of waste, lining of the container, addition of any necessary absorbent, keeping account of and limiting the amount of liquid that goes into a container, labeling, etc., are done by either a representative of the "Authorized User" or the departmental waste manager, depending on specific departmental procedures.
   

Waste Collection and Storage in the Laboratory (top)

Prior to the startup of radioisotope use in a laboratory, the "Authorized User" must contact the Office of Environmental Health and Safety to arrange for a waste disposal orientation session for the "Authorized User" and appropriate laboratory personnel. During the orientation session, waste disposal categories and procedures are explained, and a decision is made concerning the particular types of waste disposal containers to be placed in the laboratory, based on laboratory needs and financial considerations.

The following procedures and guidelines are applicable to the laboratory collection and storage of any form of radioactive waste, regardless of the manner of final disposal:

1. The date, radioisotope, and amount of radioactive materials placed in a waste container must be recorded on a waste record card, EHS-HP Forms 210 - 215, or on an equivalent form. A reasonable but conservative estimate of the activity is sufficient if an accurate figure is not possible. Waste is not acceptable for disposal unless it is accompanied by a completed waste record card.
2. Radioactive wastes may not be placed into waste containers intended for non-radioactive wastes.
3. Radioactive material waste containers should not be used for non-radioactive wastes nor should they be used as disposal containers for other toxic wastes.
4. Each radioactive material waste container in the laboratory, once it has been designated for use for a particular type of radioactive waste, i.e., liquid scintillation counting waste, solid decay-in-storage waste, long-lived solid waste, etc. should be labeled to indicate its designation.
5. The chemical compatibility and hazard characteristics of radioactive wastes placed within the same container should always be considered.
6. Fermentation and degradation of biological radioactive wastes should be minimized with the addition to such wastes of bleach or other appropriate disinfectants.
7. Radioactive material waste containers shall be placed in a safe location to prevent damage and should be kept well separated from non-radioactive material waste cans to avoid cross-contamination.
8. Careful consideration should be given to external dose rates created by gamma, neutron and high energy beta emitters placed in the waste containers. It may become necessary to shield the materials or the waste container or to relocate the container to a less accessible area.
9. Only authorized radioactive material waste containers provided by the waste disposal services broker, the decay-in-storage facility operator, or approved by the "Health Physicist" may be used for waste storage or shipment. The use of other than authorized containers for waste storage within the laboratory is discouraged, since custodial personnel are trained to recognize the authorized containers, but may be allowed after consultation with the "Health Physicist."
10. Each waste container used for radioactive waste collection in laboratories and each container used for the subsequent storage or shipment of wastes shall be inspected for corrosion or damage which could affect the integrity of its containment, prior to its being placed in service. Containers used for the local collection of wastes and/or for extended periods of time shall be inspected regularly. Containers whose integrity is suspect shall not be used for waste collection or shipment.
11. The contents of each radioactive material waste container shall be inspected by a laboratory or departmental representative prior to removal from the laboratory to ensure that the wastes are properly separated and packaged in accordance with applicable procedures.

Decay-In-Storage Program (top)

The University's NRC broad license permits the University to dispose of certain radioactive materials through a decay-in-storage program, provided that various conditions are met. Under the Decay-In-Storage (DIS) Program, wastes contaminated with certain short-lived isotopes will be collected from the laboratories for storage in specially designed liquid and solid waste facilities. After storage for a minimum of ten half-lives, solid wastes are rigorously surveyed, and if no activity distinguishable from background levels is found, then the wastes are disposed of as nonradioactive medical wastes. The detailed waste disposal procedures necessary for proper segregation and packaging of DIS wastes are available from the Molecular Biology Department. The following items summarize the program:

1. Radioisotopes permitted to be disposed of through the Solid Waste Decay-in-Storage Program must have half-lives < 90 days. This includes radioisotopes such as P-32, P-33, S-35, Cr-51, and I-125.
2. Radioisotopes permitted to be disposed of through the Liquid Waste Decay-in-Storage Program must have half-lives of < 90 days. This includes P-32, P-33, S-35, Cr-51 and I-125.
3. Only containers obtained through the DIS Program may be used for the collection of DIS liquid and solid wastes in the laboratory. These containers, which are clearly labeled as DIS containers, may be obtained from the DIS Facilities operator.
4. Wastes contaminated with short-lived isotopes and intended for disposal through the DIS Program must be strictly segregated in the laboratory from all other radioactive wastes. DIS wastes themselves must be segregated by isotope to as large an extent as possible. Waste from an experiment with dual labeling, e.g., utilizing a short-lived isotope such as P-32 and a longer-lived isotope such as H-3, must be disposed of as radioactive waste through the Interim Radioactive Waste Storage Program rather than as DIS waste.
5. High activity (multimillicurie) waste materials should be separated from lower activity materials in the laboratory to decrease the volume of wastes that must be stored in the DIS Facilities for more than ten half-lives.
6. Before an item is placed into a DIS solid waste container, radioactive materials labels must be removed, if possible, or thoroughly obliterated or covered. Wastes containing items with visible radioactive materials labels will not be accepted for storage in the DIS facilities.
7. Liquid scintillation counting wastes contaminated with short-lived isotopes are not stored separately as DIS wastes. Due to low disposal costs for liquid scintillation counting wastes and the complexities of the DIS procedures, all liquid scintillation counting wastes, regardless of the contaminating isotope, are picked up and disposed of by the waste disposal service vendor.

Liquid Scintillation Wastes (top)

1. Liquid scintillation wastes (including wastes contaminated with short-lived isotopes) are transported for disposal by the University's radioactive waste disposal services broker. Specific procedures for the packaging, storage and disposal of liquid scintillation wastes are available from the Office of Environmental Health and Safety.
2. Only liquid scintillation counting solutions with flashpoints of 140oF or greater are acceptable for disposal. A list of acceptable counting solutions is available from the Office of Environmental Health and Safety.
3. Waste collection of filled 30- and 55-gallon drums is made by the broker, as needed, and is scheduled through the Office of Environmental Health and Safety. Approximately two weeks before a scheduled pickup, the Office of Environmental Health and Safety contacts "Authorized Users" or departmental waste managers, as appropriate, to determine the number of waste containers to be picked up and the number of replacement containers to be delivered.

Off-Site Disposal of Long-Lived Solid Wastes (top)

The Office of Environmental Health and Safety administers a contract for the off-site disposal of any long-lived solid radioactive wastes. General features of the off-site disposal program are described below. The detailed waste collection and packaging procedures for long-lived solid wastes are available from the Office of Environmental Health and Safety.

1. Wastes which must be disposed of through the Off-Site Long-lived Solid Waste Disposal Program include solid wastes contaminated with any radioisotope with a half-life greater than 90 days.
2. Most of the University's long-lived solid waste is ultimately packaged and shipped in 30- and 55-gallon drums. Some wastes may be compacted and sent out for processing such as shredding or incineration in order to reduce waste volumes prior to final disposal.
3. Special arrangements must be made for the disposal of wastes which include discrete radioactive sources, radium, radium-contaminated objects, thorium and uranium compounds, and transuranics.
4. Anyone who is contemplating the use of radium and transuranics should be aware that it may be extremely costly or, in some cases, impossible to arrange for the disposal of radium and transuranic wastes. Users should also be aware that uranium and thorium compounds, especially thorium nitrate or uranium nitrate, are easily obtainable but are difficult to dispose of.
5. The generation of non-routine wastes, such as odd-shaped, exotic, or unusually large materials, require that the Office of Environmental Health and Safety be contacted as soon as the disposal need is recognized so arrangements can be made for shipping containers and for special handling.

Sanitary Sewage System (top)

Use of the University sanitary sewage system as a primary means of radioisotope waste disposal is prohibited except under very specific conditions. The careful control of sewer disposal is necessary because the permissible water concentrations established by regulations are extremely low. The disposal of certain isotopes is permitted, however, subject to the following conditions:

1. General Requirements
   • No radioactive material may be placed into the sanitary sewer unless it is aqueous and readily soluble in water or readily dispersible biological material.
   • The pH of any materials added to the sewer must be greater than or equal to 5 and less than or equal to 9.
   • A record of all sewer disposals must be kept and reported monthly to the Office of Environmental Health & Safety on EHS-HP Form #203, the Radioactive Waste and Release Report. These data are used to ensure the University's compliance with monthly average concentration and yearly total limits.

 

2. Specific Sewer Waste Streams

   The general requirements stated above apply to each of the specific waste streams described below:

• Disposals via the Liquid Waste Decay-in-Storage Facility Disposals must be made in accordance with the Decay-in-Storage Facility operating procedures approved by the Radiation Safety Committee.
• Secondary Disposals

The secondary disposal of radioactive material to the sanitary sewer is defined as the disposal of liquids containing low concentrations of radioactive materials, including rinses of contaminated glassware and other equipment and the disposal of very small amounts of radioactivity in large volumes of liquid, e.g. sequencing buffer solutions.

The "secondary disposal" of any radioisotope by an "Authorized User" is permitted, provided the following conditions are met:

1. The combined total activity, regardless of isotope, for all "secondary disposals" made by each "Authorized User" and all persons using radioisotopes under his or her authorization must not exceed 100 µCi per day, when averaged over a seven day week.

2. For each specific individual isotope, the total activity per day, when averaged over a seven day week, in all "secondary disposals" made by each "Authorized User" and all persons using radioisotopes under his or her authorization must not exceed the amount specified in the following table:

Radioisotope	"Secondary Disposal" Limits (uCi)
H-3	100
C-14	100
P-32	10
P-33	100
S-35	100
Ca-45	100
Cr-51	100
I-125	1

The "Health Physicist" must be consulted for "secondary disposal" limits for other radioisotopes.

3. The "secondary disposal" of radioactive materials using sinks in an "Authorized User's" laboratory is permitted provided that the sinks have been labeled for "secondary disposal" by the Office of Environmental Health & Safety. The "Authorized User" is strongly encouraged to designate only one or two sinks to be used for "secondary disposal."

4. An "Authorized User" may apply to the Office of Environmental Health & Safety to request exceptions to the "secondary disposal" activity limits. Such requests for exceptions may be approved, subject to review by the "Health Physicist" on a case-by-case basis, and subject to limitation such that the University will not exceed the overall activity release limits established by regulation.

Primary Disposals

The primary disposal of liquids to the sanitary sewer is defined as the disposal of radioactive liquids under conditions which do not meet the criteria for "secondary disposals," i.e., the disposal of quantities in excess of the limits in paragraph 15.D.2.b.(2) or the disposal of relatively high concentrations, regardless of activity.

1. At present only the "primary disposal" of H-3 and C-14 is permitted. If the "primary disposal" of liquids containing long-lived isotopes other than H-3 and C-14 becomes necessary, the "Health Physicist" may approve such disposals on a case-by-case basis.
2. The "primary disposal" of any isotopes with half-lives less than 90 days is not permitted. Such isotopes are disposed of through the Decay-in-Storage Program.
3. Only designated sinks, which have been specifically approved and labeled by the Office of Environmental Health & Safety, may be used for "primary disposals." Each department is strongly encouraged to carefully limit the number of sinks which can be used for "primary disposal."
4. The Office of Environmental Health & Safety must be notified in advance of any primary disposal. It may occasionally be necessary to put limitations on the amount of H-3 and C-14 which can be disposed of in a given day in order to limit the daily average concentrations to meet sewer authority regulations.

Mixed Wastes (top)

Mixed wastes are wastes containing both radioactive materials and hazardous waste components regulated under RCRA (the Federal Resource Conservation and Recovery Act). Currently no disposal site licensed for the disposal of radioactive wastes is also licensed to accept hazardous wastes for disposal. Consequently, mixed wastes are prohibited from land disposal, and the options for disposing of mixed wastes are extremely limited and essentially nonexistent.

In the laboratory setting the types of mixed wastes most likely to be generated include contaminated lead and certain organic solvents such as chloroform, phenol, xylene, and toluene. It is the responsibility of the "Authorized User" to ensure that wastes presented for disposal through the centralized radioactive waste disposal program do not contain mixed wastes. The Office of Environmental Health and Safety is available to help an "Authorized User" make a determination about the nature of his or her wastes.

If the generation of mixed wastes is unavoidable, then the "Authorized User" must contact the "Health Physicist" to establish waste packaging and storage procedures for those materials.

All "Authorized Users" are strongly encouraged to use laboratory techniques or to develop new techniques which do not result in the production of mixed wastes.