HAZWOPER 40 - Lesson 6 Radiological Hazards(solved)

Lesson Description Often the most neglected and misunderstood types of monitoring on hazardous waste sites are radiation hazards and monitoring. Therefore, waste site workers should understand radiation hazards and different types of radiation. This Radiological Hazards lesson introduces radiological hazards to help workers to choose the type of protection necessary for any type of radiation hazard they may encounter in the workplace. It categorizes radiation types and examines radiation dosage and units. Sources of radiation exposure are described along with their effects. The lesson then focuses on radioactive contamination and concludes with a discussion of radiation protection Learning Objectives At the completion of this lesson, you will be able to: Identify and categorize radiation types. Explain radiation dosage and units. Identify sources of radiation exposure. Classify and describe radiation dosage. List the most radiosensitive cells. Outline the effects of radiation exposure. Describe the three states of radioactive contamination. Apply radiation protection principles to protect yourself and others from radioactive material. Introduction Unlike many of the other hazards present on a hazardous waste site, detection of radiation is solely dependent on monitoring by instrument. Although not commonly considered the primary hazard on most waste sites, radioactive materials may be present in drums, including lab packs (pre-packaged materials that are being exposed of in a larger container), in either solid or liquid form. Waste from hospitals and research facilities in particular, should be suspected of containing ionizing radiation. Waste tailings from mineral processing and oil and gas facilities may also be contaminated with Naturally Occurring Radioactive Material (NORM). In order to avoid exposure, it is important that workers realize the precautions that must be taken when dealing with radiological waste or sources. Lesson Focus This lesson focuses on the following topics: Radiation Types Radiation Dosage and Units Sources of Radiation Exposure Radiation Dosage Radiation Exposure Radioactive Contamination Radiation Protection Radiation Types Radiation is categorized as either ionizing or non-ionizing. Both are energy waves (ionizing radiation can also exist as particles); nevertheless, non-ionizing radiation contains less energy. The major types of radiation emitted as a result of spontaneous decay are alpha and beta particles, and gamma rays. X-rays, another major type of radiation, arise from processes outside of the nucleus. Non-Ionizing Radiation This includes radiant heat, radio waves, ultraviolet radiation, and light. Waste site sources of non-ionizing radiation (Microwaves) include welding (which emits strong visible light and ultraviolet radiation) laser instruments (which are used for measuring and leveling) and radio equipment including radar. Radiation emitting equipment should be used with proper precautions. Ionizing radiation has sufficient energy to remove electrons from atoms. In this lesson, it will simply be referred to as radiation. One source of radiation is the nuclei of unstable atoms. For these radioactive atoms (also referred to as radionuclides or radioisotopes) to become more stable, the nuclei eject or emit subatomic particles and high-energy photons (gamma rays). This process is called radioactive decay. Unstable isotopes of radium, radon, uranium, and thorium, for example, exist naturally. Others are continually being made naturally or by human activities such as the splitting of atoms in a nuclear reactor. Either way, they release ionizing radiation. This decaying is caused by instability within the nucleus of the material. Ionizing Radiation Ionizing radiation has many uses (e.g. X-rays, measuring soil density metals analyzers, and food pasteurization). The three types of ionizing radiation are: Alpha Beta Gamma Radiation (Video) Radiation Dosage and Units Radiation doses are measured using standard radiation units. These units are: the Roentgen (R), rad (Radiation Absorbed Dose), and rem (Roentgen Equivalent Man). The Roentgen is defined only in terms of the ionizing effect on air and applies only to X-rays and gamma rays. It does not relate to the effect of radiation on the human body. The rad measures the absorbed dose (i.e., the amount of ionizing radiation (any type) absorbed into a material). The rad does not take into account the potential effects that different types of radiation have on the body. The rem is the most commonly used unit of measure and is used for dose equivalence. It takes into account the difference in the potential human biological effects produced by different types of radiation. Sources of Radiation Exposure On a daily basis, the human body must deal with these exposures. At a properly monitored worksite, the occupational exposure that workers could receive is but a small portion of the exposure with which the body is already successfully dealing. Any release of radioactive material is a potential source of radiation exposure to the population. Radiation exposure is often measured by a dosimeter badge worn by the employee. In addition to exposure from external sources, radiation exposure can occur internally by ingesting, inhaling, injecting, or absorbing radioactive materials. Both external and internal sources can irradiate the whole for those body or a portion of the body. This exposure can be monitored through routine urinalysis while employees are on a project where contaminated particulate exposure is possible such as during soil remediation. The amount of radiation exposure is usually expressed in a unit called the millirem (mrem). In the United States, the average person is exposed to an effective dose equivalent of approximately 360 mrem (whole-body exposure) per year from all sources (NCRP Report No. 93). Dose Rates Radiation units include a time factor, and are commonly referred to as dose rates. These can be expressed as follows: R/hr or mR/hr (mR/hr is 1/1000th of the unit R/hr) Rad/hr or mrad/hr Rem/hr or mrem/hr Radiation Dosage When we talk in terms of dosage in radiation, we use the same terms found in toxicology i.e. amount of exposure times the duration of exposure (quantity x time). We also classify radiation doses as acute or chronic. Chronic Dose Chronic doses are small amounts of radiation over a long period of time, such as our normal daily exposures over our lifetimes. We know that the body is able to tolerate a chronic dose better than an acute dose. Acute Dose Acute doses have a greater effect on us because the body does not have time to repair or replace the damaged body cells. An acute dose of 10,000-25,000 mrem could cause slight blood changes, but a normal individual would not be otherwise affected. An acute dose greater than 100,000 mrem causes half of the exposed population to experience nausea (due to damage to the intestinal lining). This is common in radiation therapy patients. Acute doses greater than 500,000 mrem may cause so much body damage that the body cannot recover. For example, the firefighters at Chernobyl are estimated to have received doses in excess of 800,000 mrem. This, compounded with the burns they received, caused them to succumb to the effects of their injuries.