PAGE 1 OF 5 HEALTH, SAFETY & ENVIROMENTAL MANUAL PROCEDURE: S560 Radiation Safety REV /14/2012

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1 PAGE 1 OF 5 RADIATION SAFETY PURPOSE: A wide usage of x-ray machines and isotopes for examination of steel plate fabricated and erected structures require a knowledge of the radiation hazard and the precautionary measures to take to prevent exposure to the radiation hazard. PROCEDURE: Definitions In order to better understand what the hazards are, there are certain definitions that must be known. 1. Radiation: Alpha rays, beta rays, gamma rays, X-rays, neutrons, highspeed electrons, high-speed protons, and other atomic particles; but not sound or radio waves, visible, infrared or ultraviolet light 2. Radioactive material: Any material which emits, by spontaneous nuclear disintegration, corpuscular or electromagnetic emanations. 3. Restricted Area: Area that is access controlled to prevent unintentional employee exposure to radiation. 4. Unrestricted Area: Area that is not access controlled to prevent unintentional employee exposure to radiation. 5. Roentgen R: A unit of radioactive dose, or exposure. It measures the penetrating external radiation only in the air. 6. Milliroentgen (MR): 1/1000 of a roentgen. 1 r = 1000 mr. 7. Rad: means a measure of the dose of any ionizing radiation to body tissues in terms of the energy absorbed per unit of mass of the tissue. One rad is the dose corresponding to the absorption of 100 ergs per gram of tissue. 8. REM: A measure of the affect of radiation on the body in terms of one roentgen of X-rays, and is used for all types of radiation. 9. Dose: The quantity of ionizing radiation absorbed, per unit of mass, by the body or by any portion of the body. 10. Dosage Rate: Dosage rate, or dose rate, is the time rate at which a dose is administered. That is, dose per unit time. Dosage rates are expressed in roentgens per minute or multiples or submultiples of these units, such as milliroentgens per hour (mr hr).

2 PAGE 2 OF 5 Control of Hazard To understand the effects of radiation, we must first understand what the significance of time; distance and shielding a source have upon exposure. When the effects of these factors are known, proper controls can be introduced to limit one or all and thereby prevent a needless accident. A. Effect of Time The effect of time on radiation exposure is easy to understand. If we are in an area where the radiation level (as measured by a radiation meter) is 50 milliroentgens per hour, then in 15 minutes we could get 12.5 milliroentgens of exposure. If we stayed 30 minutes, we would get 25 milliroentgens, and if we stayed one hour, we would get 50 milliroentgens. Time is important in determining the safe limits since knowing the length of time that the x-ray or gamma source will be in operation will enable us to calculate the allowable radiation level and then, with the use of a radiation survey meter, we can rope off the area where there will be excessive radiation levels. B. Effect of Distance The effect of distance on radiation is determined by the INVERSE SQUARE LAW. That is to say, the intensity of radiation falls off by the square of the distance from the source. Example: If we had a point source of radiation giving off 1000 milliroentgens per hour at a 1 foot distance, we would receive 250 milliroentgens per hour at a distance of two feet from the source because we have doubled the distance and the effect on the radiation level is to reduce it to 1/2 squared or 1/4. When we have tripled the distance, we have reduced the level to 1/3 squared or 1/9 to III milliroentgens. This shows us that there is a rapid fall-off in the rate of radiation exposure as we go away from the source of radiation and a relatively very small distance can go a long way in increasing our safety factor. C. Effect of Shielding 1. The use of shielding materials affords an excellent means for controlling personnel exposure in radiographic operations. Shielding material is used to absorb or stop radiation. Materials commonly used to shield radiation are concrete, iron or steel, and lead. Water is used in operations where it is necessary to see through the shielding material and to work through it with special tools and devices. Heavier materials are more effective for shielding radiation than are lighter materials such as aluminum and soil. 2. Now that you know the effect of time, distance and source shielding, you must know how to utilize this knowledge in protecting personnel from

3 PAGE 3 OF 5 D. Film Badges overexposing themselves to radiation. There are a number of safety devices that will help you in maintaining a controlled area wherever there is examination of weld or metal by radiation. 1. The film badge consists of a packet of sensitized film placed in plastic or metal holders that contain one or more filters imbedded in the holder. The worker wears the badge for a definite period of time, usually one week, at which time the film packet is replaced by a new one, and the used packet is sent to the office. The office, in turn, sends the film packet to an independent laboratory that processes the film. By reading the density (blackening of the film), they can determine the amount of radiation the badge received. These values are reported back to the original office sending them so that a continuous record can be kept of the worker's accumulated dose. 2. Film badges provide a permanent record of radiation exposure, but not an immediate one, because of the time required for shipping, developing the film, and reading the badges and transmittal of reports. E. Dosimeters A dosimeter is a radiation-detecting instrument, about the size of a fountain pen, that can be conveniently carried in a pocket or attached to the worker's clothing. They are particularly adaptable for situations where the advantage for permitting the wearer to read his accumulated dose at any time warrants the additional expense. These tiny pocket chambers will keep a continuous record of the worker's accumulated dose. Some dosimeters can be read directly by holding them up to the light. Others must be read in a reading device provided for the purpose. This enables the worker to find if it is possible under normal conditions to receive more than the safe tolerance dose and act accordingly. F. Survey Meters 1. A survey is a radiation-detecting instrument that is provided with a meter, making it possible to place the instrument in a field of radiation and immediately determine the intensity of the radiation at that location. 2. The dial of the meter is usually calibrated in milliroentgens per hour so that by knowing the intensity of the radiation at that point, it is possible by multiplying this intensity reading by the length of time the worker will be in the location, to determine the dose the worker will receive.

4 PAGE 4 OF 5 3. It should be noted that the survey meter must be recalculated every three months. Restricted Areas 1. Use of a survey meter or other appropriate survey measure shall determine the extent of the area to be restricted. Radiation in this area shall not exceed the dose limits specified in OSHA section table G No unauthorized personnel may enter Restricted Areas. Restricted areas shall be marked and barricaded with signs bearing the radiation symbol and the words Caution- Radiation Area to prevent unauthorized entry. 3. Any person who enters a restricted area and may be exposed to a significant amount of radiation as defined by OSHA (d)(3)(ii) must be issued an appropriate personal monitoring device for recording exposure to radiation. Training 1. All personnel who will be working in or near restricted areas must be familiar with the symbol which denotes radiation hazard: 2. Employees who are exposed to radioactive material must: a. Be familiar with the safety controls in place to protect their health including keeping exposure limits low, shielding, time of exposure and distance from the source. b. Understand the possible negative health affects of radiation exposure. c. Be aware of the presence of the radioactive material. 3. In the event of an emergency involving radioactive material an emergency signal will sound to prompt evacuation of the area. All persons working in the areas affected by this alarm shall be familiar with it s sound at that location. 4. Documented record of individual exposure is kept and distributed for employees who have been exposed to radiation. Individuals who have worked in areas requiring exposure documentation shall be aware of these records and their right to receive copies.

5 PAGE 5 OF 5 X-ray and Radiation Exposure Records Under the OSHA regulations, all companies performing radiography must maintain daily x-ray exposure data and radiation exposure data. These reports must be maintained for all persons who require personal monitoring devices per OSHA Exposure data must be communicated to affected employees at a minimum interval of one year. Requirements 1. Only authorized and trained the Company personnel shall operate equipment used for radiographs, No unauthorized employee is permitted to handle or use equipment that could expose the person to the hazards of ionized radiation. 4. All employees should be aware of potential radiation sources within their work area (such as lever controllers and other instrumentation). 5. Should an accidental exposure to a source of whizing radiation occur, it must be reported to the supervisor immediately. 6. If there is a hazard of radioactive materials being carried in the air, stay upwind. Do not eat, smoke or drink in the area. 7. In case of fire, summon fire-fighting personnel and stay out of fumes or smoke. 8. If radioactive containers are broken, stay away and notify customer representatives and the Company management and safety. 9. Do not remove potentially contaminated equipment until it has been deemed safe to be removed.