SAFETY
Outsmarting Those Atomic H a z a r d s With proper care, radioactive materials can handled as safely as ordinary chemicals N E W A R K , N . J . - B y use of only reasonable techniques, radioisotopes can b e handled as safely as common, everyday chemicals, says Louis G. Stang, Jr., of Brookhaven National Laboratory, speaking at t h e recent safety forum of the ACS N o r t h Jersey Section. In dealing with radioisotopes, h e says, the individual must guard against exposing himself t o radiation above the so-called maximum permissible level—that is, the level beyond w h i c h a n observable change is produced in a living organism. An excessive a m o u n t of radiation, especially b y alp h a and beta rays, produces a reddening of the skin, which may b e accompanied b y destruction of oil glands in the skin. This effect is similar to a sunburn, excerpt t h a t it takes several weeks to heal. At a somewhat higher radiation level, an ulcer of t h e skin m a y b e prod u c e d . T h e s e ulcers are characteristically very slow a n d difficult to heal. Nausea or radiation sickness is also a frequent symptom, as is a lowering of
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the white cell c o u n t of t h e blood a n d the loss of hair o n irradiated skin. These changes are all reversible, so that healing does take place in d u e time. However, if the radiation level is increased still further, the organism ultimately lapses into coma a n d dies. W h e n radiation is received internally by t h e injection of a radioactive substance, the s y m p t o m s d e p e n d o n t h e physiological, chemical, and radiation properties of t h e material. Since many ,substances are excreted r a t h e r rapidly in the u r i n e or nasal mucous, they are relatively harmless. Others, because of their physiological properties, lodge in such areas as t h e thyroid gland or t h e bone marrow, w h e r e t h e y may eventually cause cancer. A number of variables c a n b e controlled in g u a r d i n g against radiation hazards of a particular material. These include time, distance, a n d shielding. F o r t h e individual, t h e problem is to k e e p his radiation exposure below 5 0 mr. p e r day or 3 0 0 p e r week.
Radioactive materials can be handled safely; here's how it's done: H. O. Banks, Brookhaven National Lab, places a pellet of several millicuries of radioactive material into a centrifuge tube for chemical processing. Tube is held with tongs, and pellet with tweezers to reduce radiation received by hands. Lab coat and surgeon's gloves protect body from contamination. Film badge clipped to collar, ionization chambers in breast pocket, and film badge on right wrist band monitor radiation received by various parts of the body. Pellet is transported from reactor to lab in lead cylinder ( left ). Four lead bricks between pellet and operator serve as a "shadow shield"
Many operations, even w h e r e fairly large a m o u n t s of radioactivity are involved, can b e performed in just a few seconds, Stang declares. Therefore, by working rapidly, t h e operator c a n often handle a fairly active material without the need for shielding. F o r example, if a source is emitting radiation of 20 r. per h r . a t a distance of 1 ft., then a person h a s 9 seconds in which to m a n i p u l a t e t h e material w i t h l-ft.-long tongs before his h a n d is exposed to the u p p e r limit of 50 mr, Usually, this type of operation can b e performed in far less time. Since radiation intensity from a point source diminishes according to the inverse square law (neglecting absorption in air a n d other intervening m a terials), radiation effects may b e controlled by u s e of distance. W i t h m a terials emitting moderate or highenergy gamma rays, t h e absorption effect in air is usually neglected. On t h e other hand, for materials emitting b e t a or soft g a m m a rays, t h e absorption effect cannot b e neglected since the radiation level decreases with distance much more rapidly t h a n might be p r e dicted by t h e inverse square relationship. W h e n it comes to shielding, a w i d e variety of materials is used. Among these, listed in t h e order of increasing shielding power, a r e water, aluminum, concrete, steel, lead, mercury, uranium, a n d tungsten. An important consideration h e r e is cost of t h e material. Although a thin section of w a t e r is relatively ineffective as a gamma shield, nevertheless a deep water-filled tank makes an excellent shield that is inexpensive to build a n d maintain a n d is also transparent a n d flexible. Not only can radioactive sources be seen u n d e r water but they can b e readily manipulated by tongs a t t a c h e d to long poles. Uranium has b e e n used in certain special cases where a particularly effective g a m m a shield is required. For example, if a wall of lead bricks is being e m p l o y e d as a shield a n d part of the brick m u s t b e cut away t o accommodate some portion of t h e a p p a r a t u s such as a control, then uranium can b e used to compensate for t h e decreased thickness. W h e n working in a radioactive laboratory, a researcher is well advised t o : • wear suitable rubber gloves, usually thin surgeon's gloves. • assume that all laboratory glassware is c o n t a m i n a t e d a n d h a n d l e it accordingly. • pick u p glassware a n d other objects with a fresh piece of p a p e r and
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Demineralized water helps G O *O D / maintain Airfoam quality-and saves money, too! T h e minerals dissolved in r a w water carry elec trolytic charges. If such water is used for latex dispersions, the rubber coagulates p r e m a t u r e l y . . . causing excessive waste. Goodyear ù i e d distilled water.., until increased production overtaxed the steam plant. So G o o d y e a r e n g i n e e r s loolced i n t o i o n exchange. After evaluating various demineralizers, they selected Permutit resins and equipment. Here's w h a t they report after 4 years of continu-
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afterward discard the paper into a special trash can. • keep bench tops and sometimes floors covered with paper that is fre quently changed. • set vessels containing liquids on trays that will contain the liquid if the vessel breaks. • be especially cautious when evapo rating liquids to dryness to make sure they don't spatter or b u m p .
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"All this sounds like a complicated business," says Stang, "but it is simply a matter of common sense. I t is sur prising how rapidly a worker becomes accustomed to using proper techniques when he realizes t h e importance of do ing so and t h e degree to which con tamination must b e controlled/' Not Accidental. An accident is not accidental in the usual sense, says W. A. Cutter of NYU. Rather, acci dents are predictable phenomena that are the result of unsafe actions or con ditions or both. He believes we fail to prevent deaths, injuries, a n d prop erty damage simply because we are not willing to develop and apply t h e same comprehensive control programs to prevention of these inefficiencies as we apply, for example, to quality and product control. I n a chemical plant, the safety direc tor is not the individual personally re sponsible for accident prevention. Rather, he is the staff adviser on acci dent prevention. H e is the analyst who discovers what no one else takes the time to discover: what is happen ing, what is likely to happen, a n d how to prevent it. T h e safety director is the coordinator of accident prevention efforts and is the person who uses all available media to maintain interest. Often, professional technical employees are the hardest people to enlist in sup port of safety programs, says Cutter.
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