Document dYX1vvDj1xd88Bbzyq6NzZXkG

qualifying statements attached to these pub lished values, for example m NBS Handbook 69, should be closely read and understood In each case, NBS Handbook 69 should be consulted for information on the specific radionuclide being used, and a plan for esti mating internal exposure from human ex cretion data should then be developed (See the list of publications under the subhead " `Radioecology' literature" under "Refer ences" at the end of this chapter) Bio-assay specimens may be analyzed by commercial laboratories Typical Industrial Installations and Operations This section gives details of how to make a specific installation safe, and how to operate it safely The suggestions and procedures have been taken from "Specific Installations and Operations," by Jack Baliff, PE It is Chapter 6 of The Control of Radiation Haz ards tn Industry, published in 1959 by State of New York, Department of Labor, Division of Industrial Hygiene X-ray installations (Industrial radiography) Plan X-ray protection prior to actual installation The primary method of control involves enclosure and shielding In the interest of economy, from the stand point of shielding material and construction costs, consider the following m planning Distance to X-ray tube The installation should be as far removed as circumstances will permit from all spaces occupied by per sons dunng operation of the equipment Spaces adjacent to the installation should, wherever practical, be restricted to storage or other purposes requiring only infrequent presence of personnel Comer locations or comer rooms are especially suited, the out side walls and windows do not require any shielding if they are sufficiently distant from other occupied buildings and areas The center of a room may not always be the best location for the installation, greater pro tection is sometimes gained by placing the equipment m a comer of the room or next to a wall bordering dead storage space Consid eration should, however, be given to future occupancy of nearby areas Direction of useful (primary) X-ray beam Wherever possible, the useful X-ray beam should be directed away from all occupied spaces Where normal operation is not in terfered with, devices for restricting the angulation of the tube may reduce the amount of shielding required Cross section of useful X-ray beam The cross section of the useful X-ray beam should be as small as practicable Whenever pos sible, cones should be used Operating conditions and workload The thickness of required shielding also depends on these two factors Thus, in addition to knowing the type and use of the proposed installation, one should know the kilovoltage, tube current, and the expected working activity of the machine The possibility of operating several machines located in the area at the same time must also be considered For accessibility and viewing, openings m radiation barriers may be necessary but these should be held to a minimum Protection for all such openings should be provided by means of suitably shielded (lead-lined) doors, leaded glass windows, or by suitable baffles equipped with mirrors Closed circuit tele vision can be used for viewing The structural shielding and general lay out requirements of any new installation, or an existing one in which changes are con templated, should be discussed with a quali fied expert early in the planning stage He should be provided with all the previous data as well as the structural details of the build ing in order to properly design the necessary shielding The design of protective barriers should be computed for the maximum kilovoltage, tube current, and the proper work load and occupancy factor It is also advis able that the final plans, detailed drawings and all pertinent specifications be checked by a qualified person before construction begins Plan structural details and layout OF radiation barriers These are an im portant part of shielding Attention must be given to these details to make sure that construction is substantial as well as to mini mize radiation leakage through the shielded enclosure Recommended construction spec- 1463