DETECTING IONIZING RADIATION IONIZING RADIATION CANNOT BE DETECTED BY ANY OF THE FIVE SENSES. ince ionizing radiation cannot be detected by human senses, special INTRODUCTION Sequipment is needed to detect and measure it. Emergency workers are furnished with instruments and devices that n emergency is an unexpected situation or record exposure to radiation. One type, the Aoccurrence of a serious nature that demands direct-read dosimeter, enables the emergency SEE immediate action. Because accidents involving worker to readily obtain readings that relate to HEAR radiation may occur at nuclear power stations, we the United States Environmental Protection need to prepare ourselves for this type of emer- TOUCH gency. This section of the training guide provides Agency (U.S. EPA) and Illinois Plan for Radio- TASTE information on radiation and how emergency logical Accidents (IPRA) exposure limits. A workers may protect themselves from its poten- second type, a luminescent dosimeter badge SMELL tially harmful effects. (LD), though not directly readable, provides a permanent record of the emergency worker’s exposure. DOSIMETRY KITS osimetry for emergency Dworkers is prepackaged to accelerate and simplify the issuing process during emer- gency situations. 24 21 RADIATION BASICS TYPES OF IONIZING RADIATION here are four basic types of ionizing radiation: alpha particles, beta WHAT IS RADIOACTIVITY AND RADIATION? Tparticles, gamma rays, and x-rays. While all types of radiation are po- tentially harmful, they differ in the manner in which they affect us. adioactivity is the natural process of unstable atoms releasing their Rexcess energy. This emission, or giving up energy, is called radiation. Alpha Particles have a very low penetrating ability and can be stopped by a Radiation can be either man-made or occur naturally in the very thin sheet of paper or the outer layer of skin. They are not an external environment. It is divided into two types: non-ionizing and ionizing. hazard, but once they are inhaled or ingested, they become very hazardous. Non-ionizing radiation is the type of radiation associated with the operation of many of the conveniences that we use in our daily lives: for Beta Particles have a low penetrating ability and can be shielded or stopped example, the energy that microwave ovens emit to cook our foods and the by thin sheets of metal or thick plastic. Depending on the energy of beta waves of energy that transmit our radio and television signals. particles, it can cause burns ranging in severity from minor (similar to a Ionizing radiation is the type of radiation associated with nuclear sunburn) to extreme (blistering similar to third-degree burns from fire). power generation. Because of its ability to cause damage to any Because beta particles are also harmful if inhaled or ingested, they are both organism, it is important to understand how to protect yourself from an internal and external unnecessary exposure. There are many additional uses of ionizing hazard. radiation, which include: medical x-ray, radioactive material used in medical diagnosis and treatment, industrial manufacturing, and in the Gamma Rays and X-rays production of many consumer products such as cigarettes, smoke detectors are waves similar to light and some gas lantern mantels. ALPHA waves, but have higher Besides the radioactive materials that are man-made, ionizing radiation energy levels. Lead, steel, BETA occurs naturally in rocks and eventually works its way into the soil, trees, concrete or water are com- plants, ground water, and even into materials in the human body. Another GAMMA important source of naturally occurring ionizing radiation is the sun and monly used to shield this outer space, which produces a continuous exposure to all living organisms type of ionizing radiation. on this planet. We call naturally occurring radiation background Although scientists make a radiation. distinction between x-rays and gamma rays, the impor- tant difference is that gamma rays are usually more energetic and there- fore more penetrating. 22 23 FRACTIONAL UNITS COLLECTION OF RADIOLOGICAL SAMPLES he fractional units, milliroentgen, millirad, and milliRem, are used to ■ Escort radiological monitoring teams T measure and describe small quantities of radiation. The prefix, “milli,” ■ Escort and/or assist sample collection personnel means 1/1000th of a roentgen, rad, or Rem. For example, 1,000 mR equals 1 R. DECONTAMINATION OF EQUIPMENT AND STREETS ■ Set up monitoring stations on perimeter of affected areas ■ Wash down vehicles, streets, etc. upon recommendation of IEMA ■ Wear normal protective gear for personal contamination protection CONTINUATION OF ROUTINE PUBLIC SERVICES ■ Law enforcement and crime prevention ■ Emergency medical services ■ Fire/rescue services in affected areas To simplify communications and the reporting or exchange of informa- tion, the terms R and mR are used instead of the scientific terminology. 26 19 UNITS OF MEASUREMENT RADIATION IS MEASURED IN THREE BASIC UNITS: Part II UNIT DEFINITION ROENTGEN (R) — The roentgen is the unit of exposure and is a measure of the ionization produced in air by gamma rays and x-rays. Direct-read dosimeters record exposure in roentgens. RADIATION ABSORBED Radiological Hazard DOSE (rad) — The rad is the unit of absorbed dose and is a measure of the energy deposited in matter by ionizing radiation. & ROENTGEN EQUIVALENT Exposure Control MAN (Rem) — The Rem is the unit of dose equivalent and is the measure that accounts for the varying effects of different types of ionizing radiation on the human body. An understanding of the differences in these units is important in the scientific study of ionizing radiation. In nuclear power station accidents or radiation emergencies, however, the terms roentgen, rad, and Rem are used interchangeably. Therefore, for this purpose, a roentgen is equal to a rad is equal to a Rem. 20 25 EXPOSURE RATE AND EXPOSURE RECOVERY, RE-ENTRY AND RETURN xposure rate is a measurement of the rate of exposure over some nsite recovery operations consist of all the steps taken to return the nuclear Eperiod of time, usually an hour. For example, if a reading from an expo- Opower station to an operational status. Due to the fact that recovery plans will sure rate meter was 1 R/hr and an individual remained in the area where this be based on the specific on-going events, much of the recovery planning will take reading was taken for one hour, the direct-read dosimeter would register an place during the emergency. Exelon will formulate the onsite recovery plans. exposure of 1 R. Offsite recovery involves the process of determining when radiation exposure rates and concentrations of radioactive material in the environment have returned to acceptable levels for the return of the general public for unconditional occupancy or use. Re-entry is the temporary entry of individuals into a restricted zone under controlled conditions. Re-entry is allowed so that necessary functions can be performed in the restricted area. Return is defined as the return of the general population to an evacuated area. This includes provisions for notification and transportation of evacuees. The emergency situation must be ended prior to return, and the evacuated area determined safe by IEMA. Environmental teams will be deployed throughout areas affected by a radiological accident at a nuclear power station. These teams will be equipped with a variety of instruments for measuring exposure rates. The readings obtained from these instruments will be relayed to an IEMA repre- sentative at each affected county Emergency Operation Center. This infor- mation will be distributed to all Dosimetry Control Officers (DCO) respon- sible for controlling the exposure of emergency workers. 28 17 FUNCTIONS OF THE EMERGENCY PROTECTING YOURSELF WORKER FROM IONIZING RADIATION he IPRA coordinates the efforts of Federal, State and local governmental T agencies. These governmental agencies are made up of personnel referred to EFFECTS OF TIME, DISTANCE, AND SHIELDING as “Emergency Workers”. The role played by these emergency workers is vital to ime, distance, and shielding, when used effectively, will help protect the successful implementation of the IPRA, and more importantly to the safety and you from ionizing radiation. welfare of the EPZ population. T Emergency workers may be assigned to perform one or more of the following Time The less time you spend in a radiation area, the less tasks: exposure you will receive. ■ For example, if you were working in an area where the PUBLIC NOTIFICATION exposure rate was 100 mR/hr and you stayed there for ■ Utilize squad cars or vehicles equipped with mobile PA systems one hour, you would receive an exposure of 100 mR. If ■ Inform citizens of recommended protective actions you remained there for only 30 minutes, you would receive an exposure of 50 mR. TRAFFIC AND ACCESS CONTROL ■ Distance The farther away you are from a source of ionizing Staff traffic and access control posts radiation, the less exposure you will receive. ■ Direct traffic ■ When assigned tasks in a radiation area are completed, ■ Monitor traffic conditions ■ Maintain access control into affected areas emergency workers will be reassigned to unaffected ■ Deliver and erect barricades locations. ■ Provide roving security Shielding The use of shielding between you and a source of ionizing ■ Maintain clear roads radiation will reduce your exposure. ■ The amount of reduction depends on the type and density EVACUATION OF GENERAL POPULATION, of the shielding material. SCHOOLS AND SPECIAL CONCERNS ■ When possible, emergency workers in radiation areas ■ Notify individuals in affected areas should take advantage of shielding behind buildings, ■ Provide bus transportation automobiles, trucks, or any other means of shelter to ■ Provide special transportation for disabled citizens, shut-ins, etc. reduce their exposure. ■ Register evacuees at Reception Centers 18 27 LEVELS OF EXPOSURE PROTECTIVE ACTIONS rotective actions are the specific actions implemented by Federal, State, county BIOLOGICAL EFFECTS OF IONIZING RADIATION Pand local emergency response organizations to minimize radiation exposure during an accident at a nuclear power station.