Document vB7eME5Dwm44GLdMyOXgoOo2m

714 LEON F. CUKTI8S at the end of this chapter. Many specific details, too lengthy to include here, wi] be found in these handbooks. , qf 6. Transportation by Common Carrier The shipment of radioisotopes by rail or air is now controlled by the IntSs? state Commerce Commission, which has authority to enforce its regulations^' the imposition of penalties for violations. This matter was taken under thef" supervision in 1947 when it had become apparent that the large volume7' artificial radioisotopes currently requiring shipment demanded more adequa control than had existed previously. The problem of shipping radioisotopes is complicated by the fact tha. undeveloped photographic film is also shipped by common carrier and is readL damaged by very small exposures to penetrating radiation. This problem already been encountered with shipments of radium. The solution consisted "iff devising a method of packing and disposition of radioactive material in tranti that would reduce the level of radiation at any point occupied by photographic film below that at which practical damage could occur. All packages of radio, isotopes must be labelled in a prescribed manner showing the nature of trn. contents and the amount of emergent radiation. These regulations are available from the Bureau of Explosives, 30 Ves'er Street, New York 7, N. Y., as Supplement No. 10 to ICC 4670. Since all SftifS ments of radioisotopes must comply with these regulations, it is incumbent prospective-shippers-to become thoroughly familiar withthem.- An- explan&io,. monograph has been prepared by Robley D. Evans, Chairman of the Sub committee on Shipment of Radioactive Substances of the Committee on Nuclei" Science of the National Research Council. This monograph is obtainable froni the National Research Council, 2101 Constitution Avenue N. W., Washington 2.1 D. C., as Publication 205. H. PROTECTION PROM X-RAYS 1. Special Features Although the problem of protecting personnel from x-radiation is sirpila in many respects to that of protecting them from gamma rays, actual condifebris frequently are very different. Physiological effects to be expected are mu8|||fe same, aftd tolerance doses are measured in the same unit. Where the intensjti and energies of the radiations differ considerably from those usually encounter^ with gamma rays from radioisotopes or accelerators, the details of protective -arfa-ngements^musli-be-modified-to-correspond-:----------------------------------- -- The source of x-rays, the x-ray tube, because of its more extensive volume" and the necessity of providing electrical conductors, increases the difficulty"'of shielding. Such bulky sources also scatter diffuse radiation in the vicinity, -a ,, effect that is more pronounced the higher the intensities of radiation generate'! - RADIANT ENERGY 715 J&ling with the protection of personnel engaged in this work, the electrical ||;:from high potentials also must be discussed since this is about as frequent ire of injury as exposure to radiation. 2. Protection from Electric Shock ^.-industrial applications of x-rays, this problem can be divided into two ilijcases depending on the two types of generating equipment commonly used, lijhe portable or semiportable unit in which all parts are built into a single and shielded electrically. In the use of this unit, the operator cannot jdvantage of the electrical protection offered by insulating the surface of surrounding objects. Rubber shoes and gloves may reduce danger of i.some extent, but the only sure protection from shock is a continuous metal enclosure for all parts of- the unit,' so that it is quite impossible ^operator to touch any part that is not at ground potential. This includes jKiiiBuJypltage and low voltage cables, control panels, and all other exterior electrical bonds between these parts not only must insure permanent %^'tijiVai3-union of the parts, but also should be substantial mechanically. In fome^asls, a single heavy cable connecting some part of the grounded system to ^permanently earthed point, such as a water pipe, may be sufficient. However, ^ojne types of equipment, high frequency currents may develop that will ing||>arks to ground unless several grounds are used at frequent intervals. ygnt second type of x-ray generating equipment, which is less, common, is |||m.pne or more rooms, requiring all "work to be -brought to the x-ray tube. 0$ Sphe general rules apply to this equipment, but greater precautions must be fere parts cannot be permanently shielded. If the high voltage is generated pirate room, provision must be made so that it is,-mot possible to enter the^tubfi-room with the generator in operation. Also, a cut-off switch should be ** it"' id-i-near the tube to prevent energizing the high-voltage transformer when is in the tube room. If high voltage conduptdifSj?are >not enclosed in iMijjshields, they must be at a sufficient distance1.f5pm .all points where m fitjfthay normally walk that there is no possibility, of injury from a spark, jpefance is about 71/afeet/fprHy;oltagps belpw?225-. kjloyplts and congspoqd- Sgreater for higher .arg.-^pecomjnended, to ^ippsconditioni of ;the-generating'e^pmeiS"and''sE6ul'CErio'aTrahged i||ji]ffvmisinterpretation. In all cases a pilot light should indicate-when the &itch.controlling the generator is closed. Smrlpad circuit breakers of :a. sensitive and quick-acting type should be Wii Ugontrol panel of all x-ray generators should be located so.that the x-ray,. Completely in view of the operator. This may be accomplished by some, /indirect viewing device to screen the operator from scattered radiation; S^irn