13.0 RADIATION SAFETY
The following sections provide general safety guidelines and procedures for radiation safety. This chapter covers the following topics:
 | Radiation Safety at UTIA |
| Radioactive Materials |
| Lasers |
| Microwaves |
| Radiation-Producing Devices |
| Ultraviolet Lamps |
Appreciation is expressed to Office of Radiation Safety personnel for their assistance.
UTIA maintains strict requirements for working with sources of radiation. The radiation safety program at UTIA protects employees, students, and visitors as well as the public and the environment from the harmful effects of exposure to ionizing and nonionizing radiations. The Office of Radiation Safety (ORS) governs the protocol and use of radioactive materials and radiation-producing devices on campus.
Any faculty or staff member who desires to work with radioisotopes or radiation-producing devices must apply for and receive a permit from the ORS. In addition, their employees and other employees who work with sources of radiation must receive formal training in equipment operation, safety guidelines, and emergency procedures.
The document titled "Basic Radiation Safety - A Guide for Researchers at UTK" is available from the ORS.
The purpose of the document "Basic Radiation Safety - A Guide for Researchers at UTK" is to establish the policies of UTIA with regard to the use of licensed radioactive materials. These policies apply to sealed sources as well as to open isotopes regardless of physical or chemical form.
- Radioactive materials may only be possessed by or under the supervision of individuals who have been formally permitted by the ORS.
- Permit Holders or their designees shall obtain approval from the ORS before placing an order for radioactive materials. Approvals are also required before Permit Holders receive radioactive materials via transfer from another licensee, via donations, etc.
- All sources of radiation shall be secured from unauthorized access or removal.
- All radioactive wastes shall be disposed through the ORS or via written procedures approved by the ORS.
- All persons are responsible for safe working practices and for maintaining their own exposures to ionizing radiations As Low As Reasonably Achievable (ALARA).
- Each user is responsible for reporting unsafe practices and/or rules violations to the Permit Holder or, if responses are not satisfactory, to the ORS or the Tennessee Division of Radiological Health.
- ORS personnel are on duty 24-hours per day, 7 days per week. For incidents or emergencies which occur after normal business hours, contact Roy P. Osborne (865) 675-0382, or the Knoxville Police Department (911).
- Permit Holders and users of radioactive materials shall comply with all aspects of the Radiation Safety Program Policy Manual.
The State of Tennessee regulates the use of lasers through the Tennessee Division of Radiological Health.
Lasers present many safety threats, but the most common threat is damage to the eyes. Other common laser concerns include skin damage, electrical hazards from high-energy power sources, chemical exposure, fire/explosion hazards, and exposure to cryogenic materials such as hydrogen and oxygen. Many lasers emit invisible ultraviolet or infrared radiation.
Lasers are classified into four basic categories:
| Class 1. Lowest power lasers that do not emit hazardous levels. |
| Class 2. Low-power lasers that pose a hazard only if viewed directly for extended periods. |
| Class 3. Medium-power lasers that pose moderate risk and can cause injury. |
| Class 4. High-energy, high-risk lasers that can cause injury to the eyes and skin from direct or diffused reflection. |
NOTE: If you work with a class 3 or 4 laser, you must register the laser source with the UTIA Safety Office.
Laser devices require engineering controls to ensure safety. All Class 3 and 4 lasers require a combination of protective housing, area warning signs, or remote firing capabilities.
The following information is required for registering the laser.
| classification of the laser device. |
| wavelength of the laser output. |
| power output. |
| appropriate eye wear. |
Follow these guidelines when working with Class 3 and Class 4 lasers.
- Never aim a laser at a person.
- Be very careful when working with hand-held laser pointers.
- Do not allow children access to pointers.
- Wear protective clothing such as eye wear and skin protection, as appropriate.
- Post warning signs at entrances where lasers are present.
- When working with power supplies, remove jewelry, stand on a dry surface, and work with only one hand at a time. Observe high voltage precautions (see Electrical Safety chapter).
- Control access to areas where lasers are used (i.e., no spectators).
- If possible, enclose the entire laser beam path on Class 4 lasers.
Microwaves are part of the electromagnetic spectrum; they range in frequency from 300 megahertz (MHZ) to 300 gigahertz (GHz). Microwaves are used for communications, radar, intrusion alarms, door openers, and medical therapy, but they are most commonly used for cooking.
Metal reflects microwave radiation, but dry nonmetallic surfaces allow microwaves to pass through with little or no heating effect. Organic materials, however, are extremely heat conductive. Because microwaves can penetrate organic materials, including tissues, thermal burns, and other effects may result from microwave exposure.
NOTE: Microwave ovens are very safe when kept in good working condition and used properly. They do not serve as a source of exposure to harmful microwaves. Even though microwave ovens are not a source of harmful radiation exposure, they should be properly used and maintained.
- Do not put metal objects (including aluminum foil) into a microwave oven.
- Do not use a microwave oven if it is damaged.
- Ensure that the seal on a microwave oven is tight, intact, and in good condition (i.e., not charred or distorted).
- Ensure that microwave ovens are clearly labeled for laboratory use or food preparation only.
- Microwave ovens should only be repaired by trained personnel.
13.6 Radiation-Producing Devices
Radiation-producing devices such as x-ray machines, electron microscopes, and particle accelerators are regulated through the Tennessee Division of Radiological Health. All radiation-producing devices must be registered with the Office of Radiation Safety.
Radiation-producing devices (other human and veterinary diagnostic devices) shall be interlocked to prevent access to the unshielded beam during normal or routine operations. Exceptions may be granted by the UT Radiation Safety Committee.
IMPORTANT: The door(s) to a room where a radiation-producing device is located, should be posted with a radiation warning sign, unless the device is totally self-contained.
Ultraviolet (UV) lamps are useful germicidal tools, but they also pose a potential health hazard. The following sections provide essential safety information for working with UV lamps and light.
13.7.1 Health Hazards
Exposure to UV radiation can cause extreme discomfort and serious injury. Therefore, you must protect your eyes and skin from direct and reflected UV light. Pay particular attention to laboratory surfaces, such as stainless steel, that can reflect UV light and increase your UV exposure.
The effect of UV radiation overexposure depends on UV dosage, wave length, portion of body exposed, and the sensitivity of the individual. Overexposure of the eyes may produce painful inflammation, a gritty sensation, and/or tears within three to twelve hours. Overexposure of the skin will produce reddening (i.e., sunburn) within one to eight hours. Certain medication can cause an individual to be more reactive to UV light.
13.7.2 Personal Protective Equipment
Adequate eye and skin protection are essential when working around UV radiation. Before entering a laboratory with ultraviolet installations, you must turn off the lights or wear protective equipment (e.g., goggles, cap, gown, and gloves).
NOTE: Safety glasses with side shields or goggles with solid side pieces are the only equipment that provide adequate eye protection against direct and reflected UV light.
13.7.3 Germicidal Function
UV radiation is particularly useful in the laboratory when combined with other methods for decontamination and disinfection. UV radiation is used primarily to reduce the number of microorganisms in the air and on surfaces. It is most effective against vegetative bacteria.
UV rays can only kill organisms that are invisible to the naked eye. To be effective, UV rays must directly strike the microorganisms. If microorganisms are shielded by a coating of organic material (e.g., culture medium), the UV light will be ineffective.
13.7.4 Maintenance
Ultraviolet lamps lose germicidal effectiveness over time and may need to be replaced even though the lamp has not burned out. It may be necessary to replace the lamp according to the manufacturer's recommendations. There are two types of UV lamps---hot cathode and cold cathode. The hot cathode lamp has two pins at each end and the cold cathode lamp has one pin at each end. Manufacturers recommend that hot cathode lamps be replaced every six months and that cold cathode lamps be replaced every 12 months.
In addition to replacing UV lamps as indicated above, follow these guidelines to maintain UV lamps:
- Regularly wipe cool, unlit UV lamp bulbs with a soft cloth moistened with alcohol. (Dust can decrease the effectiveness of a UV lamp.)
- Do not touch a UV bulb with your bare hands. The natural oils on your hand may leave a fingerprint and create dead space on the bulb's surface.