Quick Guide to Radioactive Waste Disposal at Middlebury College

Accumulation and disposal of all radioactive wastes must follow the requirements of Middlebury’s Standard Operating Procedures for Radioactive Waste Disposal. This guide provides a simplified version of those requirements for ease of use.

For information about procedures that aren’t discussed here, or to find about what happens to the waste after it leaves your lab, please refer to the complete Standard Operating Procedures.

Each person who is listed as a user on Middlebury College’s Radioactive Material License is responsible for ensuring that all wastes from his or her laboratory are properly accumulated and packaged for disposal.

This involves making sure that wastes are accumulated and disposed only in licensed laboratories and within prescribed limits, verifying that all wastes are segregated by half-life and certain physical and chemical characteristics, and maintaining proper logs and other documentation for the waste.

For more information, speak with Tim Allen, Radiation Safety Technician, or Tim Wickland, RSO

Accumulation and disposal of radioactive wastes in laboratories

Radioactive wastes may be accumulated or disposed only in designated Limited Access Areas and not in any Occasional Use Areas. To determine which catergory your lab falls in, please see Authorized Work Areas.

The NRC permits direct disposal of certain low-level radioactive wastes, including some that can be discharged to the sanitary sewer, within strictly defined limits. Before accumulating a specific waste for disposal, you should check whether one of the immediate disposal methods listed in paragraph A or B below is applicable to that waste.

A. The wastes listed below may be disposed via the sewer only via designated laboratory sinks in Limited Access Areas, and only if all of the following conditions are met:

1) The quantity of waste discharged must not exceed any of the activity limits listed in Table A in the Appendix to this guide, and

2) the waste must be completely dissolved in water before disposal, or must be miscible with water in all proportions. Also permissible: A biological waste (such as blood) may be dispersed in the aqueous waste rather than dissolved, and

3) the waste must not be flammable, toxic, contain heavy metals, or otherwise be subject to EPA, Vermont DEC, or other regulations as a hazardous waste, and

4) any pathogenic or infectious agent in the waste must be rendered non-viable.

The types of wastes acceptable for sewer disposal are:

1) water?soluble waste supernatants or fluids from any experiment involving radioactive materials, or

2) water-dispersed biological wastes contained in such supernatants or fluids, or

3) decontamination washes and rinses of glassware and apparatus used in such experiments.

Note that so-called aqueous scintillation cocktails are not fully miscible with water, and may not be disposed via the sanitary sewer.

B. Animal carcasses containing only 3H or 14C at a total concentration of 0.05 mCi or less per gram averaged over the body weight of the entire animal will be incinerated.

C. Radioactive wastes that cannot be disposed by one of the immediate methods listed above must be accumulated for eventual disposal in an appropriate waste container in a designated Limited Access Area. All waste containers are to be kept closed except when adding waste.

D. Radioactive wastes generated in an Occasional Use Area cannot be accumulated in that area but must be transferred to a designated Limited Access Area at the end of each experiment.

Segregation of radioactive wastes

In order to permit proper disposal, wastes need to be segregated into separate containers according to both the half-life of the radionuclide (Half?life Category) and the type of waste (Waste Category). The second category includes the physical form of the waste and any contamination it may have with other hazardous substances. Most users will only need to separate waste by half-life and physical form (liquid or dry). However, you should know that, in general, the greater the variety of materials and number of different nuclides you use, the greater the number of separate waste containers you will need to maintain.

The following categories are to be used to segregate wastes by half-life. To determine the half-life category for a given waste, use the longest-lived nuclide included in the waste. Unless samples need to be labeled with multiple radionuclides, however, please do not combine radioactive wastes with different half-life categories in the same waste container, as this makes disposal more expensive.

Half-life Category	Actual half-life	Applicable nuclides for which we are licensed
LONG	t1/2 > 90 days	3H, 14C, 45Ca, 54Mn, 55Fe
90	90 days ? t1/2 > 60 days	35S
60	60 days ? t1/2 > 30 days	125I
30	30 days ? t1/2 > 15 days	86Rb
15	15 days ? t1/2 > 5 days	32P
5	5 days ? t1/2	24Na, 42K

The most common Waste Categories are listed in Table B of the Appendix. If your waste is not described exactly in this table, you will need to refer to the complete Standard Operating Procedures for more information. In any case, be sure you understand the applicable waste categories before you begin to accumulate any radioactive wastes.

Once you have determined the number of waste categories you have, you will know how many separate waste containers you need. The following are the requirements for waste accumulation containers for laboratories. All containers are to be kept closed except when adding waste.

• Solid radioactive wastes must be accumulated in closable containers lined with the labeled heavy yellow polyethylene radioactive waste bags available from the stockroom. Do not use ordinary trash bags.

• Bulk liquid wastes are to be accumulated in suitable closed containers. Liquid accumulation containers must also stand in leakproof trays capable of containing 1-1/2 times the volume of the largest container in the tray.

• Scintillation fluids must remain in their plastic counting vials—do not empty. As a con-venience in handling, vials should be replaced in their original packing trays, if available.

• In addition to the requirements listed above, all 32P wastes are to be accumulated in plastic containers, and shielded behind of materials of low atomic number such as 3?8? thick acrylic plastic or polyethylene, in order to minimize Bremsstrahlung radiation.

Documentation of radioactive wastes

All radioactive waste disposal, including disposal into the sanitary sewer or via animal carcasses, must be recorded in the Radioisotope Use Log. Any inadvertent disposal of radioactive waste into the sewer in excess of the designated limits must be logged and reported immediately to the RSO or Radiation Safety Technician.

In addition to the Radioisotope Use Log, the user must maintain Radioactive Waste Logs for wastes that are accumulated in the laboratory. A separate Radioactive Waste Log must be kept for each waste container, listing the nuclide and amount of activity placed in the container; this log must be updated at the end of each experimental procedure. If the waste contains chelating agents (EDTA, DPTA, citrates, etc.) at concentrations greater than 0.1% by weight, the total weight of these agents must be accurately estimated and listed on the log.

Each radioactive waste accumulation container or waste receptacle located in a laboratory must be marked with the words “Radioactive Waste” and the radiation symbol, and must be kept closed except when adding waste. Containers should also be labeled with the warning “Do Not Empty.” In addition, the container must be clearly labeled with the proper Half-life Category and permitted radionuclides, as well as in accordance with the Waste Category segregation requirements described in the Standard Operating Procedures or listed in Table B of the Appendix to this guide.

Transfer of wastes to the radioactive waste facility

The Radiation Safety Technician will supervise transfer of all radioactive wastes to the waste facility and, together with the Radiation Safety Officer (RSO), will verify that wastes are properly disposed according to Federal regulations and the requirements of our waste handler. Users must arrange a time in advance before delivering radioactive wastes to the Bicentennial Hall waste facility. All wastes must be accompanied by a properly completed Radioactive Waste Internal Manifest (RWIM) for each container of waste delivered.

You must obtain the names of all the radionuclides in the waste bag or other container, their total activities, and the amounts of any chelating agents from the Radioactive Waste Log for that container and declare the totals on the RWIM. The Radiation Safety Technician will inspect the waste and approve the RWIM before accepting the waste. Any waste which appears not to meet proper accumulation guidelines will be refused; such problems would include but not be limited to signs of moisture in dry waste containers, bags which are too full to be closed properly, or apparent discrepancies in the Radioactive Waste Log or RWIM.

Problems with stored wastes

You will be contacted if any problem arises with your waste while it is in storage. You may be asked to assist with any necessary remedies as well. Such problems might include the discovery of waste that is unacceptable for your declared Waste Category, or evidence that declared short-lived waste may be contaminated with long-lived nuclides. An investigation into the problem will be initiated by the RSO, and until the investigation is complete, no further wastes will be accepted from you.

If the investigation finds either that contamination of the waste with undeclared long-lived nuclides has occurred or that the amount of permitted short-lived nuclides actually in the waste differs from the amount you declared on the RWIM, you will be asked to immediately cease all use of radionuclides until further investigation resolves how the errors occurred, and until assurances satisfactory to the RSO are made that the errors in question will not recur.

See the Standard Operating Procedures for more information.

Appendix

Table A – Permitted discharges of radioactive effluents from designated Limited Access Areas:

		Maximum	NRC-permitted effluent concentrations		Permitted release from EACH Limited Access Area†
Nuclide	Half-life	amount allowed on site	Air, µCi/ml	Release to sewer, µCi/ml	Release to sewer, µCi/day	Maximum release to sewer, µCi/year
3H	12.3 y	250 mCi total 100 mCi per sample	1 x 10^-7	1 x 10^-2	28,000	5 x 10^5
14C	5,730 y	50 mCi	3 x 10^-9	3 x 10^-4	840	1 x 10^5
24Na	15 h	1 mCi	7 x 10^-9	5 x 10^-4	1,400
32P	14.3 d	10 mCi	1 x 10^-9	9 x 10^-5	252
35S	87.2 d	50 mCi	2 x 10^-8	1 x 10^-3	2,800	1 x 10^5 combined total for all nuclides other than 3H & 14C
42K	12.4 h	1 mCi	7 x 10^-9	6 x 10^-4	1,680
45Ca	165 d	1 mCi	1 x 10^-9	2 x 10^-4	560
54Mn	312 d	1 mCi	1 x 10^-9	3 x 10^-4	840
55Fe	2.7 y	1 mCi	3 x 10^-9	1 x 10^-4	280
86Rb	18.6 d	1 mCi	1 x 10^-9	7 x 10^-5	196
125I	59.9 d	5 mCi	3 x 10^-10	2 x 10^-5	56

† Note: The table above has been taken from our “Standard Operating Procedure for Radioactive Waste Disposal” and applies TO EACH of the following ten (10) designated Limited Access Areas in Bicentennial Hall: 343, 348, 349, 352, 355, 362, 363, 449, 452, and 465. This table would no longer apply if more than a total of ten (10) Limited Access Areas were to be designated, nor would it apply to any Limited Access Areas at locations other than in Bicentennial Hall, should any be so designated. The dilution factor for each Limited Access Area is based on a total Bicentennial Hall wastewater generation of 2.8 x 10^4 L/day or 8.5 x 10^5 L/month.

Table B – Waste Categories for the most commonly used waste types

In order to permit wastes to be readily and properly disposed at the lowest possible cost, it is essential that the listed segregation categories be strictly adhered to.

For radioactive wastes consisting only of materials with a half-life of 90 days or less, the following Waste Categories must be used to further segregate the wastes into separate waste containers when accumulating your wastes for disposal. All wastes in this section will be held for 10 half-lives to permit decay and then disposed as either EPA hazardous waste or ordinary waste, as appropriate.
Category DW-Hold Short-lived dry and wet wastes; must be non-hazardous	Solid dry waste with small amounts of absorbed or pourable aqueous liquids, wet items (vials, test tubes, etc.), and/or aqueous liquid waste in vials containing 50mL or less of liquid. There must be no organic solvent contamination, no heavy metals or other EPA hazardous waste, and no long-lived radioactive wastes. Any pathogenic or infectious material must be rendered non-viable.
	Very Important! All radioactive labels, warning legends, and symbols on any item must either be removed or completely defaced before the item is placed inside the waste collection bag or container!
Category SO-Hold Scintillation Vials	Liquid Scintillation vials containing radionuclides having a half-life of 90 days or less and containing no radioactive wastes of any other kind.
Category L-Hold Aqueous Liquids	Aqueous wastes having an activity level in excess of that which may be discharged to the sanitary sewer, but with no organic solvent contamination, no heavy metals, azides, cyanides, or other EPA hazardous wastes, and no long-lived radioactive waste. Any pathogenic or infectious material must be rendered non-viable.
For radioactive wastes that contain any material with a half-life greater than 90 days, the following categories must be used to further segregate the waste. All wastes in this section will be shipped to an appropriate radioactive or hazardous waste site for disposal. All Hold Category wastes will be held for decay of the short-lived component(s) prior to final disposal.
Category D Dry Waste Only	Solid dry waste with no absorbed or pourable liquid of any kind, no wet items (vials, test tubes, etc.), no animal carcasses, and no organic solvent contamination. If the waste contains chelating agents (EDTA, DPTA, citrates, etc.) at concentrations greater than 0.1% by weight, the total weight of these agents must be accurately estimated and declared.
Category L Solidified Liquids	Aqueous liquid waste with a pH between 6 and 9 solidified using an approved solidification agent. There must be no organic solvent contamination and no other radioactive waste of any kind. Any pathogenic or infectious liquids must be rendered non-viable. If the waste contains chelating agents (EDTA, DPTA, citrates, etc.) at concentrations greater than 0.1% by weight, the total weight of these agents must be accurately estimated and declared.
Category SX Scintillation Vials	Scintillation vials with a specific activity for 3H or 14C of 0.05µCi or less per gram of medium, and with no other radioactive materials present.
Category SX-Hold Scintillation Vials	Scintillation vials with a specific activity for 3H or 14C of 0.05µCi or less per gram of medium and any mixture of radionuclides having a half-life of 90 days or less, with no other radioactive materials present.