No. 7 - September 8, 1998

1. Have You Seen Our Web Page?

If you have access to the web be sure to check out the Radiological Health Department web page. You can find it under the University's web page. Just click on "Faculty/Staff," then select "Radiological Health" under "Service Departments." Or, you can tune in directly at http://www.rso.utah.edu. On our web page, you can check out our personnel, training information, the latest version of all the RPRs and the Radiation Safety Manual, and there are many links to other web sites that contain interesting information on radiation safety. You can also use our web page to request a radioactive waste pickup, in case you're bored using the telephone.

2. Some Tips on Radioactive Waste

Most of the questions we are asked (and most of the problems we encounter) concern radioactive and mixed waste. Here are a few tips about waste that might help you avoid some of the pitfalls.

(1) Waste Tags - You may have noticed that the top (yellow) copy of our newest version of the radioactive waste tag (RPR 13E) is identified on the bottom as the "Generator's Copy." Our technician who picks up your radioactive waste will initial and date the tag where it says "acceptance date." He will then tear off the generator's copy and give it to you, or leave it in the lab if no one is present to accept it. Please keep that copy in case questions arise later about that particular waste package.

(2) Lead Pigs - Most folks have probably heard the word by now about mixed waste. Mixed waste is that stuff that contains both radioactivity and some chemical that the EPA has designated as a hazardous waste. Mixed waste is a particular problem for everyone for two reasons. First, it's usually much more expensive and more difficult to dispose of mixed waste than it is to dispose of ordinary radioactive waste. Second, the EPA gives us a very short time period in which to get rid of mixed waste, which usually drives the disposal cost up even more. As it turns out, lead (yes, metallic lead) is one of those EPA hazardous wastes. That means that you don't want to toss any lead pigs into the radioactive waste, even if they are contaminated with radioactivity. Keep them separate from your radioactive waste and we will handle them for you. Be sure, however, to tell us what isotope the pig is contaminated with. We will even pick up and recycle your non-contaminated lead pigs if you don't need them. (NOTE: Never put any lead pigs, even clean ones, into the ordinary trash).

(3) Uranium & Thorium Compounds - Sometimes folks need to discard uranyl nitrate, uranyl acetate, thorium nitrate or other chemical compounds containing natural uranium or thorium. If the waste is an unused (or partially used) container of the compound, please keep it separate from your other radioactive waste, since we have to handle each differently. Also, please identify it on your waste tag as "natural uranium" or "nat-U," or "natural thorium" or "nat-Th," rather than try to identify it by isotope. Also, please include on the waste tag the chemical form (i.e., nitrate, acetate, oxide, etc.), since we must handle each form somewhat differently.

(4) Segregate Your Radioactive Wastes by Half-Life - If your lab uses several different radionuclides including tritium or carbon-14, you need to think about segregation by half-life. When we pick up your radioactive wastes we take them to our waste management facility. There all short-lived radioactive wastes (i.e., wastes containing radionuclides with half-lives of 120 days or less) are "held for decay." After sufficient time has passed for the radioactivity to decay awa,y we dispose of the waste as ordinary trash (which is why it's important for you to remove all radioactive labels from short-lived wastes). The result is that, other than labor, disposing of short-lived wastes costs us very little. Wastes containing the commonly used radionuclides P-32, P-33, S-35, Cr-51 and I-125 are all short-lived wastes.

On the other hand, wastes containing H-3 (tritium) and C-14, both of which have long half-lives, must all be packaged and shipped to the State of Washington for final disposal. This is not cheap - figure about $900 per drum plus labor, transportation and plus several expensive permit fees. Quickly you realize that, if you use both long and short-lived radionuclides in your lab, it's very smart to keep the long-lived and short-lived wastes segregated. In that way we can store your bag of short-lived waste for decay and package your bag of long-lived waste for shipment. We don't like to ship a whole drum of decayed-away short-lived waste to the permanent waste disposal site in Washington just because it has a tiny amount of H-3 or C-14 in it. So, please segregate your radioactive waste by half-life. You'll notice that our waste tags are set up for you to indicate which category your waste falls into.

(5) Keep Good Waste Records - Occasionally we're asked to pick up a radioactive or mixed waste where the lab personnel have no idea what's in the waste. This often occurs with "legacy waste," which is that unlabeled stuff you found in the back of the cabinet under your hood. Since none of us are clairvoyant this creates a real problem. It can also be an expensive problem if we have to hire a lab to analyze the waste. To avoid this problem please keep your various waste containers segregated, well labeled, and keep good records on whatever is placed into a waste container.

(6) Protect Your Lead Bricks - If you use lead bricks for shielding work with dispersible radioactivity you should be concerned about contaminating the lead. This can be avoided if you wrap each brick with plastic wrap or aluminum foil before stacking the bricks.

(7) Mercury Thermometers - If you need to use a thermometer in contact with any dispersible radioactive material please avoid using a thermometer containing mercury. If the thermometer breaks and the mercury becomes contaminated you might create a mixed waste nightmare. Use an alcohol thermometer instead.

(8) Don't Mix Iodine Waste with Acids or Oxidizers - If you accumulate liquid radioiodine (I-125 or I-131) waste in your lab be sure to avoid mixing any acids or oxidizers (such as bleach) with it. Acids or oxidizers can cause radioiodine to evolve into the air, where it can become an inhalation or contamination hazard. For the same reason, do not use any decontaminating solution containing bleach or acid for cleaning up radioiodine spills. Instead, please use ordinary liquid detergent or a neutral or basic pH product, such as "Lift-Away" (TM - Research Products International Corp., Mount Prospect, IL).

J. J. Thompson

09/08/98