Presentation on theme: "Chapter 21 Radiation Hazards. Major Topics Exposure of employees to radiation Caution signs and labels Evacuation warning signal Storage and disposal."— Presentation transcript:
Chapter 21 Radiation Hazards
Major Topics Exposure of employees to radiation Caution signs and labels Evacuation warning signal Storage and disposal of radioactive material Reports of records of overexposure OSHA standards for health and environmental controls
Ionizing radiation: radiation, restricted area, dose, rem and radiation area Radiation: consists of energetic nuclear particles and includes alpha rays, beta rays, gamma rays, X-rays, neutrons, high speed electrons, and high speed protons. Restricted area: is any area to which access is restricted in an attempt to protect employees from exposure to radiation or radioactive materials. Dose: is the amount of ionizing radiation absorbed per unit of mass by part of the body or the whole body. Rem: is a measure of the dose of ionizing radiation to body tissue stated in terms of its estimated biological effect relative to a dose of one roentgen ® of X-rays. Radiation area: is any accessible area in which radiation hazard exists that could deliver doses as follows: within one hour a major portion of the body could receive more than 5 millirems, or within 5 consecutive days a major portion of the body could receive more that 100 millirems.
Maximum whole body dose during a calendar quarter for a 17 year old individual Individuals under 18 years of age may receive only doses that do not exceed 10 percent of those specified in fig 21-2 (page 482) in any calendar quarter. No more than 10% of 1.25 = rems per calendar quarter for a 17 year old.
Personal monitoring devices Employers must conduct comprehensive surveys to identify and evaluate radiation hazards present in the workplace from any and all sources. Employers must require the use of appropriate personnel monitoring devices by the following: Any employee who enters a restricted area where he or she is likely to receive a dose greater than 25% of the total limit of exposure specified for a calendar quarter. Any employee 18 years of age or less who enters a restricted area where he or she is likely to receive a dose greater than 5 % of the total limit of exposure specified for a calendar quarter. Any employee who enters a high radiation area.
Caution signs The universal color scheme for caution signs and label warning of radiation hazards is purple or magneta superimposed on a yellow background. Both OSHA and NRC require caution signs in radiation areas, high radiation areas, airborne radiation areas, areas containing radioactive materials, and containers in which radioactive materials are stored or transported. Fig 21-3 page 483 shows the universal symbol for radiation. Along with the appropriate warning words, this symbol should be used on signs and labels. Fig 21-4 on page 483 shows a warning sign and label that may be used in various radioactive settings. On containers, labels should also include the following information: quantity of radioactive material, kinds of radioactive material, and date on which the contents were measured.
Required evacuation warning signal Companies that produce, use, store, or transport radioactive material are required to have a signal generating system that can warn of the need for evacuation. The signal shall be mid frequency complex sound wave (between 450 and 500 Hz) amplitude modulated (between 4 and 5 Hz) at a subsonic frequency. The signal generator shall not be less than 75 decibels at every location where an individual may be present whose immediate, rapid and complete evacuation is essential. A sufficient number of signal generators must be installed to cover all personnel who may need to be evacuated. The signal shall be unique, unduplicated, and instantly recognizable in the plant where it is located. The signal must be long enough in duration to ensure that all potentially affected employees are able to hear it. The signal generator must respond automatically without the need for human activation, and it must be fitted with backup power.
Radioactive material stored in a non-restricted area Radioactive material stored in unrestricted areas “shall be secured against unauthorized removal from the place of storage.” The radioactive materials should not be handled and transported, intentional or inadvertent, by persons who are not qualified to move them safely. The disposal of radioactive material is also a regulated activity. There are only 3 ways to dispose radioactive waste: transfer to an authorized recipient, transfer in a method approved by the Atomic Energy Commission (AEC), or transfer in a manner approved by any state that has an agreement with the AEC – fig 21-5 page 485.
Incidents that require immediate notification concerning radiation overexposure A radiation related incident must be reported if employees meet a specific set of requirements: Exposure of the whole body of any individual to 25 rems or more of radiation; exposure of the skin of the whole body of any individual to 150 rems or more of radiation; or exposure of the feet, ankles, hands, or forearms of any individual to 375 rems or more of radiation. The release of radioactive material in concentrations which if averaged over a period of 24 hours would exceed 5000 times the limit specified. If an incident meeting one of these criteria occurs, the employer must notify the proper authorities immediately. Companies regulated by the Atomic Energy Commission are to notify the commission. Companies in states that have an agreement with the AEC (fig 21-5) are to notify the state designee. All other companies are to notify the US assistant secretary of labor. Telephone or telegraph notifications are sufficient to satisfy the immediacy requirements.
Written report of radiation overexposure In addition to the immediate and 24 hour notification requirements, employers are required to follow up with a written report within 30 days. Written reports are required when an employee is exposed to radiation or when radioactive materials are on hand in concentrations greater than the specified limits. Each report should contain the following material as applicable: extent of exposure of employee to radiation or radioactive materials; levels of radiation and concentration of radiation involved; cause of the exposure; levels of concentration; and corrective action taken. Whenever a report is filed concerning the overexposure of an employee, the report should also be given to that employee, with the note that ”You should preserve this report for future reference.” Records of the dosage of radiation received by all monitored employees must be maintained and kept up to date. Records should contain cumulative doses for each monitored employee (fig 21-6 page 486). Such records must be shared with the employee at least annually. Cumulative radiation records must be made available to former employees upon request within 30 days.
Non ionizing radiation Non ionizing radiation encompasses visible, ultraviolet, infrared, microwave, radio and ac power frequencies (10 15 Hz or less). Radiation at these frequencies can cause blisters and blindness. There is mounting evidence of a link between non ionizing radiation and cancer. The warning symbol for radio frequency radiation is shown in fig 21-7 page 489.
Concern regarding non ionizing radiation Visible radiation: This can be a hazard to employees whose job requires color perception. Eight percent of male population is red color blind and cannot properly perceive red warning signs. Ultraviolet radiation: most common source is the sun – can cause sunburn, skin cancer, and cataracts. Precautionary measures include sunglasses that block out ultraviolet rays and protective clothing. Other sources include lasers, welding arcs, and ultraviolet lamps. Infrared radiation: creates heat. Heat stress, dry skin and eyes. Primary sources are high temperature processes such as production of glass and steel. Radio frequency (RF) and microwave (MW) radiation: there is insufficient energy to ionize biologically important atoms. Microwave frequencies makes your skin feel warm. RF radiation may penetrate the body. Use of RF and MW radiation includes cellular phones, high frequency welders, communication transmitters, radar transmitters, and microwave drying equipment. Extremely low frequency (ELF) radiation: Some inconclusive epidemiological studies have suggested increased cancer risk. Lasers: Hazards include thermal threat to the eyes and the threat from electrocution of the power source. Smoke created by lasers in some processes can be toxic. Video display terminals (VDT): Concern persists about the long term effects of prolonged and continual exposure.
Anecdotal and scientific evidence linking EMF to cancer Studies have shown that some employees exposed to high magnetic fields have increased cancer rates. Many studies report small increases in the rates of leukemia or brain cancer in groups of people living or working in high magnetic fields. Other studies have found no such increase. Scientists cannot be sure whether the increased risks are caused by EMF or other factors.
Nuclear Regulatory Commission The Nuclear Regulatory Commission is an independent federal regulatory agency responsible for licensing and inspecting nuclear power plants and other commercial uses of radioactive materials. The NRC’s primary responsibility is to ensure that workers and the public are protected from unnecessary or excessive exposure to radiation and that nuclear facilities including power plants are constructed to high quality standards and operated in a safe manner.
Summary Terms related to radiation are: radiation, radioactive material, restricted area, dose, rad, rem, personnel monitoring devices, radiation area. Radiation is typically measured in rems. Employers must require the use of personnel monitoring devices such as film badges. Caution signs are required both by OSHA and the NRC. Companies that produce, use, store, or transport radioactive material must have signal generating devices to warn workers in case of an accident. Employees must be informed and instructed regarding potential radiation, precaution, and records of exposure. Radioactive materials must be appropriately labeled. Radiation incidents beyond prescribed limits must be reported immediately or within 24 hours. They must be reported in writing within 30 days to U.S. Nuclear Regulatory Commission (NRC).
Home work Answer questions 4, 5, 7, 8 and 12 on page List the situations in which caution signs are required of employers. 5. Describe in OSHA’s language, the required evacuation warning signal. 7. Describe the incidents that require immediate notification concerning radiation overexposure. 8. List the required contents in a written report of radiation overexposure. 12. What does the Nuclear Regulatory Commission do?