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Answer to Question #8583 Submitted to "Ask the Experts"Category: Industrial Radiation — Industrial Exposures The following question was answered by an expert in the appropriate field: Q
What is the recommended safe distance for someone to stay away from a site where radiography is being done in the examination of steel pipes or other welding processes? In particular, how far away from the source of radiation must a person, who is not wearing a radiation dosimeter (a member of the public), be when x-ray imaging is taking place in an open area? These types of x rays would be covered by ANSI Z54.1-1963, "Safety Standard for Non-Medical X-Ray and Sealed Gamma Ray Sources," which is referred to in the OSHA regulations, like 1910.252(d)(1)(vii) and (2)(ii).
A
The guidance document ANSI Z54.1-1963 will tell you to set (adjust) the distance (boundary) away from an x-ray source so that a member of the public (nonbadged person) will not get more that 2 millirem in an hour, and not more than 100 millirem in a year. (A millirem is a dose of radiation. Each person in the United States gets an average of 1 to 3 millirems per day from medical and natural radiation exposure.) The safe separation (boundary) distance depends on (1) the intensity of the x ray or gamma radiation source, (2) how long the source must be used to get a proper image (how long the x-ray machine must be turned on, or how long a gamma radiation source must out of its camera [portable-shield]), and (3) any added shielding used to reduce the radiation dose rate around the source of x rays or gamma radiation. Usually a licensed and trained radiographer uses a radiation survey meter to measure the dose rate around the item being x rayed and then sets up a rope boundary to keep people (members of the public) away from the open area where the x-ray images are being made. You can purchase the document, ANSI Z54.1-1963, from ANSI at its Web site or from the IHS Standards Store. John P. Hageman, MS, CHP
Answer posted on 19 October 2009. The information and material posted on this Web site is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Web site. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.
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