Industrial Radiography
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RADIATION PROTECTION OF WORKERS Industrial Radiography RADIATION AND RADIOGRAPHS RADIOACTIVE SOURCES PROCEDURES RADIOGRAPHERS DO follow the procedures. Ionizing radiation can pen- Materials of higher den Sealed sources are small þ Safe storage Precautions þ DO use the appropriate equipment, including collimators. in size and contain material etrate objects and create sity absorb more radiation. þ DO confi rm that there are no other people working in the images on photographic The metal components are which emits penetrating area of radiography. fi lm. The technique is revealed inside this tele radiation continuously. Radioactive sources should be kept in a secure, fi re þ DO use clear working signs and signals. called radiography and phone because they have Special containers made þ DO set up the controlled area and the necessary barriers. the processed fi lms are absorbed more radiation of dense metal shielding resistant and adequately shielded storage location þ DO confi rm the location of the source, or that X rays are called radiographs. than the surrounding plastic. are necessary to store, not being generated, by use of a survey meter. when not in use, and should move and manipulate these þ DO secure and store the source or X ray machine when sources. Due to their small be kept separate from other not in use. materials. The storage loca- size and manoeuvrability, Portable and mobile radiographic þ DO wear your personal dosimeter. sealed sources can be containers. ~ tion for X ray machines that used in confined spaces. are not in use is not required to be shielded. OTHER WORKERS Iridium-192 is a common radioactive source used þ DO observe the access restrictions, however remote it may in gamma radiography. Removal and return of sources to a storage location seem from the location of the source. Other radioisotopes can must be recorded. Records on the location of the þ DO familiarize yourself with all the warning signs and be used depending on Radiography sources are typically incorporated into ‘pigtails‘. The pigtail sources must be kept and updated each working day. signals the radiographers use. the density of material may be about the same size as a to be radiographed. þ DO report any safety concerns to the Radiation Protection pencil but the actual source (circled, Cooperation with other workers Offi cer. above) is physically smaller. þ DO NOT tamper with or remove radiographic equipment. The radiographer needs X RAY MACHINES the cooperation of others The radiographer should Industrial radiography to ensure safety during the confi rm that people are ex DOSE AND EFFECTS requires penetrating X or work and the site manage luded from the areas where A radiographer positioning the object gamma rays to reveal hid Industrial X ray machines ment’s permission to work. there is a radiation hazard, den fl aws in metal objects typically operate at more and X ray machine. Units of dose than 100 000 volts. With- He/she must give advance then signal audibly when such as pipe welds. The notice to the local manag the source is about to be The unit of absorbed dose is the gray (Gy). terms X radiography and out electrical power, the ~The arrows on this radiograph machine does not produce ers, foremen and workers. exposed. A different signal, gamma radiography indi of a weld indicate defects. radiation and it is safe for often a beacon, should in Radiographed objects do The unit used to quantify the dose in radiation protection is cate the radiation in use. the radiographer to handle dicate the exposed radia not retain any radiation and the sievert (Sv). the equipment. A radiographer and foreman dis tion source position or, for they do not become radio One millisievert (mSv) is 1/1000 of a sievert. RADIATION PROTECTION cussing procedures for work. Note X radiography, that X rays active. They are immedi the symbols in use, including the are being generated. ately safe to handle when ► Annual doses from natural background radiation vary on plastic lead concrete radiation trefoil and legends. the test is completed. average between 1 mSv and 5 mSv worldwide. Shielding One microsievert (Sv) is 1/1000 of a millisievert. 1 cm of plastic will totally shield all ENCLOSURES AND SITE RADIOGRAPHY Warning notices and signals ► The typical dose from a chest X ray is 20 Sv. beta radiation. A radiography enclosure is Dose rate Lead and concrete can a special room construct Notices are displayed at the barriers to explain access be used to shield against restrictions and the meaning of warning signals. gamma and X radiations. ed to shield others work Dose rate is the dose received in a given time. The unit used ing outside. Warning signs is microsieverts per hour (Sv/h). Time AND devices fi tted to the Setting up X radiography. To reduce radiation doses, the time spent in radiation areas must be kept ►If a person spends two hours in an area where the dose as short as possible. The longer the time spent in an area, the higher the doors prevent accidental Allow the radiographer time A radiographer checking that the rate is 10 Sv/h, then they will receive a dose of 20 Sv. dose received. entry whilst radiation is in to check that the source is In an area where the dose rate is 100 Sv/h, the dose received will be: radioactive source is safe. use. In addition to this, pro safe or that X rays are no Health effects of radiation exposure cedures for work are fol longer being generated be Failure to confi rm that a lowed. fore you enter the area. Ra gamma source has re- If radiation doses are very high, the effect on the body will ap pear relatively soon after the exposure. These acute injuries Radiography is also carried out on-site, where objects diation does not need time tracted to the safe posi- will occur if the absorbed dose is higher than a threshold val cannot be easily moved or an enclosure is not prac- to disperse and the area is tion or X rays are not be- ue; the sources and equipment used in industrial radiography 15 minutes ticable. Provisions should be implemented to ensure safe to enter immediately ing generated can result are capable of delivering such doses. It is therefore essential 0 minutes 30 minutes 1 hour 2 hours Controlled area: Radiation No unauthorized entry that people are not present in the areas with a radia- when barriers are down. in accidental exposure. that procedures for work are followed. tion hazard. Even if the dose is not high enough to cause serious injury, The radiographer should there is still the possibility of incurring other health effects. 0 Sv 25 Sv 50 Sv 100 Sv 200 Sv Routine checks also check: These effects, e.g. radiation induced cancer, are risk based, Distance If the dose rate at 1 m from a source is 100 μSv/h the dose i.e. the higher the dose received, the greater the chance of rate at 2 m will be 25 μSv/h. The radiographer should use the survey meter to check: þ That all equipment is in developing the effect. To reduce the possibility of developing þ That the source is in its container before work begins. good condition before these effects, radiation doses must be kept: þ That the barriers are correctly positioned, or exposure starting work. AS LOW AS REASONABLY ACHIEVABLE (ALARA) rates around an enclosure are low. þ That warning signals and þ That a gamma source has retracted into the container other safety features are at the end of a gamma radiography exposure. working. þ That the area is clear at the end of site gamma þ That emergency equip- 25 Sv/h 100 Sv/h radiography. ment is available and in 1 m ~ Barriers are placed at access points above and below the location þ That X rays are no longer being generated at the end good condition. of the work. 2 m of an X radiography exposure..