WHAT YOU WANT TO KNOW

ABOUT YOUR RADIOACTIVE WASTE

Recently, several problems have come up concerning improperly sorted and mishandled waste. "What kind of problems?" you might ask, or, "what do you mean sort our waste?" I will attempt to explain some of the more common problems, why they are a problem, and what the correct procedures are to avoid them.

The first thing to realize is that radioactive waste is not like ordinary household trash. Radioactive waste is highly regulated by state and federal laws, as well as transportation and disposal site rules and regulations. It's not an exaggeration to say that all these laws, rules and regulations are very complicated and do not always follow common sense. We just have to know them. Also, we're finding that the rules often change, sometimes without much publicity. Unfortunately, if we don't know the rules, or if we overlook them, the result could be costly fines, or additional fees because of waste being rejected by the waste site.

There are two basic steps that must always be followed in managing radioactive waste. Those steps are SEGREGATION AND PACKAGING and COMMUNICATION. Segregation is done according to two characteristics, the type of material (material category) and the radionuclide half-life. In the following discussion these steps are explained in detail and the specific procedures outlined. At the same time I also describe what we do with your waste after we get it, which should help you understand why each of these steps are important.

SEGREGATION AND PACKAGING (By Material Category)

Some of the most common material category segregation problems we encounter include:

(1) full or partially full liquid scintillation (LSC) vials mixed in with dry radioactive waste.

(2) lead pigs mixed in with dry radioactive waste.

(3) needles, broken glass, pipettes or other sharp objects mixed with dry radioactive waste.

(4) containers of free-flowing liquids placed into the dry radioactive waste.

Notice that these problems have nothing to do with radioactivity. These problems are caused by the type of material that the radioactivity is associated with, or by the other stuff that might be mixed in with the waste. So, how are we supposed to segregate our waste by material category?

Refer to the Radioactive Waste Tag (RPR 13E). A copy of our waste tag is at this link. At the top of the radioactive waste tag it says "ONLY ONE MATERIAL CATEGORY ALLOWED PER PACKAGE!" That's what segregation is. Look at the tag where the seven little check boxes are. These are the material categories. Notice that the categories have nothing to do with isotopes or quantities - that comes later. The categories relate to the physical or chemical form of the waste. We have to handle and dispose of each different material category in a different way. Therefore it's essential that the different categories of waste not be mixed into a single package. Each must be separated and placed into their own individual packages. The seven different material waste categories and packaging methods are:

1. Dry, compactible, solid waste - this category includes plastic, paper, rubber gloves, plastic pipettes, empty plastic centrifuge tubes, etc. There must be NO SHARP OBJECTS, (such as needles, scalpel blades or anything that can cut or puncture the bag), NO GLASS (glass breaks easily and becomes a sharp object), NO ANIMALS OR ANIMAL PARTS, NO LIQUID SCINTILLATION VIALS (not even empty ones), NO LIQUID (except for the small one or two drop residue that unavoidably remains when you empty a container), NO HAZARDOUS CHEMICALS such as acids, bases, oxidizers (like nitrates), reactives (like sulfides), poisons, flammable or toxic solvents and NO LEAD PIGS (lead is an EPA-regulated hazardous waste).

OK, SO -

How do I handle sharp objects? That's explained in paragraph 2 below.

How do I handle glass? That's also explained in paragraph 2 below.

How do I handle animals or animal tissue? That's explained in paragraph 3 below.

How do I handle liquid scintillation vials? That's explained in paragraph 4 below.

How do I handle liquids? That's explained in paragraphs 4, 5 & 6 below.

How do I handle hazardous chemicals? That's explained in paragraph 5 & 6 below.

How do I handle lead pigs? That's explained in paragraph 7 below.

NOTE ABOUT PLASTIC BAGS: Please place your dry, compactible, solid waste into clear unmarked heavy-duty polyethylene bags. If you ask, we will give you the bags you need. If you use your own bags make certain that they are clear (no colored or opaque bags or bags with markings on them) and heavy (at least 2 mil). Clear bags are essential since we must visually inspect every bag we collect (more about that later).

2. Sharps (needles, pipets, etc.) - this category may seem self-explanatory, but it's not. Because of the potential for injury, proper handling of sharps is a very serious issue. Needles must be placed into a special plastic "sharps container," which is a special tough red polyethylene jug. But sharps also includes glassware (which can easily break and become sharp as a razor), glass pipettes (which can puncture a plastic bag even if not broken), razor blades, scalpel blades, etc. All sharps must be packaged by themselves separate from dry compactible solid waste. All sharps must be placed either into a "sharps container" or into a heavy cardboard box (corrugated). When ready for disposal the cardboard box must be securely taped shut so sharp stuff doesn't fall out or stick out. If you use a box fasten the radioactive waste tag to the top of the box with Scotch Tape or packaging tape. Please do not throw sharps in with dry waste.

3. Animal or other biological waste - this category includes animal carcasses, animal pieces and parts, blood, excreta, etc. These must be packaged separately into heavy plastic bags or cardboard boxes. Please don't include other waste in with the biological waste, especially used scalpel blades. SPECIAL NOTE: If you are disposing of animal carcasses or tissue make sure you keep the packages frozen until they can be picked up. ANOTHER SPECIAL NOTE: Please don't place more than 10 kilograms of animal carcasses or tissue into any single bag, otherwise they become difficult to handle safely. If you have a single animal carcass that weighs more than 10 kg please use your dissecting skills to divide it up into more manageable pieces.

4. Non-hazardous, non-toxic (NHNT) aqueous liquid - this category includes full or partially full LSC vials, or bulk scintillation fluid containing only the NHNT LSC cocktails that are sometimes referred to as non-flammable and biodegradable, such as Optifluor (give us a call if you don't know what these are). If you have a NHNT bulk aqueous liquid to dispose of you must collect it in a plastic (not glass) bottle (we will provide one), keep it well labeled (you don't want to accidentally mix in something that will react violently or create a "mixed waste"), and keep it in a safe place. When the bottle is full prepare a waste tag and call for a waste pickup.

How do I handle NHNT Liquid Scintillation Vials? LSC vials (empty or full) must be packaged separately from anything else. We prefer that you place LSC vials back into the cardboard trays, then place the cardboard trays into the cardboard box they originally came in. You may also place LSC vial trays, or loose LSC vials, into a clear strong plastic bag. NOTE: Please be sure the vial caps are on tight, and please do not mix paper, gloves or other trash in with the LSC vials. When we pick up the LSC vials from you we run them through an electric vial crusher which cuts open the vials and drains out all the liquid. Our vial crusher doesn't care if a vial is empty or full, however it does care if there are rubber gloves, paper towels or other junk. Junk will really mess up the machine.

5. Flammable, hazardous or toxic liquid - These liquids, which include flammable or toxic solvents such as toluene, xylene, hexane, chloroform etc., will always be MIXED WASTES if they contain radioactivity. Notice that some commercial LSC cocktails, such as Ready Value, Liquiscint, Aquasol, Econofluor, and many others, contain toluene, xylene or pseudocumene. If you're not sure whether the cocktail you're using is flammable, check the Material Safety Data Sheet, or call us. You shouldn't be using these flammable cocktails anyway, but if you have to use them, you must keep them segregated from the NHNT LSC vials.

6. Toxic or hazardous, non-flammable liquid - These liquids will include hazardous chemicals like acids and bases or solutions containing dissolved toxic metals like arsenic, barium, cadmium, chromium, lead, mercury, silver, etc. Since they also contain radioactivity, these liquids are a mixed waste. Do not mix this category with the flammable liquid category, because each category must eventually be treated in a totally different manner.

How do I handle hazardous liquid mixed wastes? First of all, try not to mix any hazardous chemicals with your radioactivity in the first place. Mixed waste is bad because we must comply with two different federal laws (NRC and EPA laws) to dispose of mixed waste, which isn't easy, and it's always expensive. Each category of mixed waste must be kept strictly segregated from any other category. Collect the liquid waste into a plastic bottle (we will provide one for you, as well as an EPA-required "Hazardous Waste" label for the bottle) When the bottle is full we will pick it up from your lab. Make certain that only one category of liquid waste is placed in a given bottle. The best policy is to call us BEFORE you even generate the mixed waste and we can give specific advice. We might even try to talk you out of generating the mixed waste in the first place, thereby saving us all a lot of money.

7. Other materials - This category would include contaminated vacuum pump oil, contaminated lead pigs, and anything else that doesn't fit into one of the previous six categories. Be sure to describe this waste material in the "DESCRIBE MATERIAL" box located on the tag below the seven categories. Call us if you aren't certain about how to categorize a particular material.

How do I handle lead pigs? Keep lead pigs all by themselves and don't mix them in with any other waste, even if the lead pigs are contaminated. Often the lead is a liner inside of a plastic container. Treat these as lead pigs and you can give us the lead and plastic together. If the lead pig contains a vial with some residual radioactivity, you can leave the vial in the pig, tape the pig closed and make sure the pig is labeled with the isotope and your best guess on how much radioactivity is left. Put all your lead pigs into a cardboard box. Above all, don't throw them into the ordinary trash can even if they are not contaminated. We will pick them up whenever we pick up the radioactive waste. We eventually recycle the clean lead. We have to handle contaminated lead in a special, unique and expensive way.

SEGREGATION (By Radionuclide Half-Life)

We also have to handle radioactive waste differently depending on the half-life of the radionuclide involved. This is because we can store radioactive waste onsite for physical decay and then dispose of it quite easily and inexpensively as ordinary trash IF the radionuclides contained in the waste have a half-life of less than (<) 120 days. For example, P-32 has a half-life of 14 days. So, after less than 5 months of storage (140 days) we can get rid of it as nonradioactive waste. The short half-life isotopes include P-32, P-33, S-35, and I-125.

Tritium (H-3) and C-14 are long-lived, so we cannot hold them for physical decay. Tritium and C-14 waste, or any radionuclides with half-lives of 120 days or longer, must be packaged into steel drums and shipped out of state for burial (at about $1000 per drum). So, if you mix the short half-life nuclides into the same package with long half-life nuclides, then we must handle the whole package as though it contained only long half-life nuclides. That wastes a lot of money unnecessarily. NOTE: To comply with our license, storing radioactive waste for physical decay can only take place in our Waste Management Building under the control of the Radiation Safety Officer. So don't try this in your lab.

How do I segregate by radionuclide? First, you have to know the half-lives of all the radionuclide(s) you're working with. If you are unsure, check RPR 10 or give us a call. If the half-life of a radionuclide is less than 120 days (I'll call it short-lived), package that radionuclide's waste separately from any waste that has a half-life longer than 120 days (long-lived). The most common example involves P-32 and H-3 or C-14, since many labs use those radionuclides. The H-3 and C-14 may be packaged together, since both are long-lived. In fact all long-lived radionuclides can be packaged together in one package. However, the P-32, or any other short-lived radionuclide, must be packaged separately, since we can store it for decay. If your investigations require the use of multiple labeling it may not always be possible to segregate your waste by radionuclide. We understand, so don't worry about it.

Should I segregate my short half-life radionuclides from each other? Yes, but this is more a question of conserving storage space, not money. All short half-life waste eventually gets disposed of as nonradioactive. However, if several short half-life radionuclides are mixed in the same waste package, we must hold that package for ten half-lives of the longest-lived radionuclide in the package. We see a lot of packages that contain both P-32 (half-life 14 days) and S-35 (half-life 88 days). In this case we are required to hold both the P-32 and S-35 for a total of 880 days (2.4 years), rather than being able to dispose of the P-32 in only 140 days (4.7 months). This makes a big difference to us in terms of the number and volume of waste packages being stored in our building. So that we can store your short half-life waste most efficiently, please segregate all your short half-life radionuclides into separate packages, according to radionuclide.

NOTE: One requirement for disposing of the short-lived radioactive waste as ordinary trash is that there be no visible radioactive labels in the package. Therefore, if your package contains the category "half-life less than (<) 120 days" then be sure to remove or obliterate all radioactive labels from the package (inside and outside). The radioactive waste tag itself is an exception because we always remove the tag ourselves. Of course, radioactive labels can remain on the long-lived radionuclides because those wastes are always controlled as radioactive.

COMMUNICATION (Filling Out The Waste Tag)

As you already know, a Waste Tag must be completely filled out before we can pick up your waste. Spend a little bit of time when you complete the waste tag and you'll save us all a lot of time later trying to figure out what's in the bag. We rely very heavily on what you put on the waste tag, so be certain it's as accurate as you can make it (accurate in the sense of stating what material and what radionuclide is in the bag. You don't have to be accurate in knowing the precise quantity. One significant figure is enough).

Several of the most common waste tag problems we encounter are:

(1) Checking more than one material category - if you've segregated properly you won't be tempted to make this mistake.

(2) Checking a liquid but not filling out the little box next to it that says "FOR LIQUIDS."

(3) Checking "Dry, compactible solid waste" and circling a vial size in the "FOR LIQUIDS" box.

(4) Checking "Dry, compactible, solid waste" and also writing the name of an LSC cocktail in the box that says "DESCRIBE MATERIAL."

(5) Writing the nuclide in the "DESCRIBE MATERIAL" box. That's repetitious - you identify the nuclide(s) on the line(s) below the box where indicated.

(6) Not paying attention to the activity units. There's a big difference between microcuries (µCi) and millicuries (mCi). If you're unsure of the difference, please ask.

(7) Confusing yourself with the Responsible User (RU). Your name goes under "Prepared by:" Your RU's name is printed on the line.

Tips for Properly Filling Out and Using the Waste Tag (it would help if you have the illustration of the waste tag in front of you as you read through this section):

(1) Check only one box according to the category in which your waste was segregated.

(2) If your waste is full or partially full LSC vials circle the size ("Mini" or "Standard") in the box titled "For Liquids."

(3) If your waste is a bulk liquid write in the size (in gallons) of the bottle (the usual choices are 1 and 2.5 gallons).

(4) If your waste is a bulk liquid write in the volume of the liquid (in gallons) contained in the bottle (if the bottle is full, then the volume of the liquid should equal the size of the container. But if the bottle is only partially full make an "eyeball estimate" of the volume of liquid).

(5) If your waste is LSC vials or bulk liquid write in the name of the LSC cocktail or the chemical name(s) of the bulk liquids in the "DESCRIBE MATERIAL" box. NOTE: if the waste is a mixed waste you must also fill out and attach a Hazardous Waste Tag. These tags are available from Environmental Health and Safety (call 1-6590).

(6) Write the symbol of each radionuclide on the line(s) indicated, such as H-3 or P-32. If you are disposing of uranyl acetate or uranyl nitrate write nat-U, not U-238. If you are disposing of thorium nitrate write nat-Th, not Th-232.

(7) Fill in the activity of the corresponding radionuclide in microcuries or millicuries, then circle which unit applies. Since the package contains waste we don't expect you to know precisely how much radioactivity it contains. Based on knowing how much activity you were handling for the processes that contributed the waste, make your best estimate of the activity to one significant figure. Please do not write "less than" (<) some number [or "more than" (>) either!].

(8) Check those Radionuclide Categories that apply, that is, (a) "H-3 and/or C-14," (b) "Half-life < 120 days," (c) "other BETA-GAMMA Emitters" (i.e., half-life greater than (>) 120 days), and, (d) "ALPHA emitters or Mass > 204." Be sure to follow the instructions for segregation according to radionuclide half-life.

(9) IF your waste contains only radionuclides with half-life less than (<) 120 days, indicate that the packages do not contain "Radioactive Material" labels by circling "No" in the box Of course, if that's not true, circle "Yes."

(10) PRINT your RU's last name on the line indicated. If you don't know, ASK.

(11) Print or sign legibly YOUR NAME next to "Prepared by:" Be sure to read the certification immediately above this section. It applies to you.

(12) Enter the date you called for this particular waste package to be picked up.

(13) Don't write in our section below the bold horizontal line, please.

(14) When we pick up your waste package our technician will enter the acceptance date and his initial, AND he will give you the top copy ("Generator's Copy"). Please keep that copy in case any questions arise later about that waste package.

WHAT HAPPENS TO YOUR RADIOACTIVE WASTE?

All radioactive and mixed waste that we collect from the labs is taken to our Regulated Waste Management Facility (Building). There the bags or boxes of solid waste are separated from the liquid wastes. We visually inspect the bags and boxes to ensure that they contain no liquids (which is why we don't like bags we can't see through). In some instances we have to manually open bags (all the non-clear ones) to do a thorough inspection, even though we don't like doing that. We also scan all bags and boxes with a metal detector to locate lead pigs. Our metal detector will find even the smallest lead pig! Dry wastes that pass our inspection and contain long-lived radionuclides are then placed into a steel 55-gallon drum. Using a hydraulic compactor we crush the waste into the drum with a force of 85,000 pounds. This ensures that we get as much waste as possible into a drum.

We ship our compacted drums to a company in California. They inspect our drums. If they don't like what they find they send the drum(s) back to us and charge us $500 (each drum) in handling fees. Next, assuming the drums pass inspection, they compact an entire full drum with a mega-compactor using a half-million pounds of force. You can imagine what would happen then if the drum contained any free liquid or full LSC vials! Next they place the squashed drum into a steel box along with about a dozen other squashed drums. Finally, they pour concrete around all the drums until the box is full. Then, after the concrete sets hard and cures, they seal up the box and ship it to Richland, Washington for final disposal by burial. For this service we pay about $1000 per drum, which is why we like to keep our volumes of long half-life waste to an absolute minimum.

I hope this provides some insight into why we have to be fussy about radioactive waste. We do expect that proper segregation and packaging, according to the rules just discussed, will take place in your lab before we come to pick up the waste. It should also be understood that radioactive waste that is not properly segregated and packaged, or has an improperly filled out waste tag, cannot be picked up. Or, if, after the waste is picked up, it is found to be improper, we will notify the originating lab. Sometimes we may have to return the package to the lab.

As always, if you have any questions about your radioactive waste, please give us a call (1-6141). We know that these rules are awfully complicated. But asking a question is never a mistake. You can also check our web page (www.rso.utah.edu) for more information or to send an e-mail question to your radiation analyst or to anyone in our department.

James J. Thompson, Ph.D., Radiation Safety Officer, 1/20/99