Document mqbDJ92e6vQY6YZQEyDeOV8VB

installation should be used In some instances (e g , where large pieces must be handled), a radiography room is not practical An area within the plant must be roped off and posted with warning signs or otherwise barricaded to prevent unauthorized personnel from entering the area Sometimes it has been found that segregating the opera tion with respect to time is the only solution to this problem, that is, to perform radiog raphy at night or other times when there are no other workmen m that part of the plant Others have solved the problem by fencing off an open area outside the buildings m such a manner that unauthorized persons cannot enter the high radiation zones Similar measures must be taken to restrict areas where radiography is performed in the field Radiation safety problems in field radi ography can be complicated by the curiosity of bystanders, the presence of other unin formed workers on the project and possible temporary misplacement of a "free" gamma source In such field applications as radiog raphing welds on pipelines, pressure tanks, refineries and other construction projects, there should be a thoroughly trained radia tion safety supervisor in charge of the work He is responsible for maintaining adequate precautionary measures to prevent unneces sary exposure of personnel Radiation warning signs should be posted and restrictive barriers erected to control traffic in the vicinity of an exposed source The warning sign should include (a) DangerRadiation, Keep Away (Do Not Loiter) and (b) the radiation symbol, Fig 44-15 Radiation safety rules should be explained to the workers and their cooperation enlisted m maintaining a safe standard of operation Where a project may be delayed by restricting the area to other workers, here again, con sideration should be given to making radiog raphs at odd hours when few or no other per sons are around The contractor should be made aware of the safe limits of radiation ex posure so that unreasonable production sched ules are not requested Generally speaking, the most important item with regard to field radiography is to make sure that the restricted site is always under surviellance by the per son in charge so that unauthorized workers, bystanders, or curiosity seekers do not enter An appropriate survey instrument should 3R FlC 44-15 --The American Standards Institute recommends this symbol for radiation warning signs Symbol should be reddish-purple, displayed against a yellow background and should be accom panied by the word "RADIATION" in yellow let ters on reddish-purple panel Radiation signs should be proportioned the same as "danger" signs and sized according to the area to be marked See ASI Standard N2 1 "Radiation Symbol " be immediately available at each field in stallation Radiation surveys of the radiog raphic setup for the purpose of establishing working times within the area should be a routine procedure m the field A survey gives the operator a quick means of determining dose rates around the site and determining where restrictive barriers should be placed Personnel monitoring, such as film badges, s also essential for those workers engaged m routine radiographic work Although misplacement ofradiation sources is not to be tolerated, it is possible for them to be accidentally dropped behind equipment and in locations where the capsule is not vis ible Small sources should therefore be tagged or labeled Where a source is mis placed, every effort should be made to re cover the source immediately without over exposure to personnel Without the use of a survey instrument, such as a geiger or scin tillation counter, it would be difficult, if not 1471