Document RV8r8a7k0KxyM0xjxoXv5MGB

IONIZING RADIATION to have been spilled and peihaps spread. Everything that leaves the plant should ho monitored, including wastes, water, air, trash, and materials in process Searches should be made wherever employees may have contaminated facilities, such as scrubup sinks, retention tanks, or doorknobs. Work clothing and other items likely to he contaminated because of their use should also be monitored In most cases, radiation and radioactive materials are easy to detect It is good practice never to assume that an item is radioactfvely dean, especially since a check can so readily be made. Even if there is little risk of injury, it makes good sense to clean contamination from die skin, hands, feet clothing, and equipment since usually only a good scrubbing is required Decontamination Decontamination is essentially a process of washing, deanmg, and safely disposing of radioactive "dirt" to dean the area or to prevent contamination of counting equip ment, research materials or equipment Since the contaminants cannot be destroyed, they most he transferred to a place where they will do no harm while they are de caying Several methods of decontamination have been used Scrubbing and washing down with a hose stream of uncontammated water will carry away easily removable contami nation. However, care should be exercised to prevent further spread of contamination by the force of die horn stream. Tenaciously adhering contaminants (grease and industrial grime) can some times be removed by scrubbing and scour ing with steam, soap, or synthetic deter gents and with dry draining solvents Absorbed or surface-reacted contaminants can be removed by chemical reagents (. cit ric, pyrophosphonc and hydrochloric adds, and their sodium salts, oxalic and nitric acids are often used as are various pro prietary decontaminating agents) which dis solve or form complexes with the contami nant or by removal of the contaminated surface (stripping paints with paint remov er, planing wood, sandpapering, burning with a blow torch, or sandblasting) in such a manner that the contaminated material can be safely collected and disposed of Consideration should, of course, be given to avoidance of chemical toxicity and flam mability in the cleaning solvents used, see Chapter 41. If decontamination is impractical, there are several possible courses of action* 1. The area may be temporarily abandoned and isolated until the radiation intensity decreases by natural decay of short halflife radioisotopes 2 The contaminated surfaces may be sealed off with spray coatings of paints or plas tics to fix the radioactive matter (not necessarily shield it) if the contaminants are alpha or beta ray emitters and there is relatively little secondary gamma- or X-radiahon to guard against later trou bles, a decal over the painted surface can indicate that contaminated surfaces are covered by the paint 3 Some contaminated articles may he dis posed of by deep bunal or by sinking in deep water m the ocean 4 Other contaminated articles may be re turned to their original service after re duction of contamination to acceptable levels After decontamination, the wash water and rubble must be carefully disposed of either by bunal in controlled areas so that it will not be dug up before it has decayed (Fig 42-17), or by isolation, or by sea disposal Really deep bunal (several thou sand feet) is under investigation for liquids and sludges Land bunal of solid wastes is commonly done at 10 to 20 feet depths If the levels are within guide limits, decon tamination wash water is often disposed by dilution and discharge to storm or sanitary sewers It generally is advisable to carry out the decontamination of large areas m two steps The first step is a preliminary careful wet ting down with plain water or water with an admixture of detergents, which wiD re move a considerable amount of the surface contamination and reduce the radiation level to make the second step safer Dry "See "Decontamination Techniques for Small Equipment," by John B Huff Nu cleonic*, 19 151-153 (Nov. 1961) 42-41