Distribution and Administration of Potassium Iodide in the Event of a Nuclear Incident (2004) / Chapter Skim
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3 Potential Exposure to Radioactive Iodine
3 Potential Exposure to Radioactive Iodine
Pages 30-43
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From page 30... ...
Radiolodine used in medical diagnosis and therapy has limited potential for use in weapons of mass destruction (dirty bombs) , and nuclear-powered submarines represent a potential for affecting public health and safety only when they are involved in accidents in port.
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From page 31... ...
, the fuel rods are placed inside an eight inch thick steel reactor vessel, the reactor vessel is contained inside a thick (several feet) , reinforced-concrete reactor building.
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From page 32... ...
Additional steps are taken in reactor design to ensure that such unexpected events as earthquakes and tornadoes do not lead to damage of nuclear fuel or release of radionuclides to the environment. These rigid design features coupled with heightened security measures make radioiodine releases from terrorist activities highly unlikely.
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From page 33... ...
Under normal operating conditions, or even accident conditions, they do not escape nuclear reactor facilities in quantities to be of concern from a public health standpoint because they do not mix readily with air and because they are easily removed Tom a reactor facility's water and air by filters. Furthermore, the rigid NPP design features discussed above are designed to prevent particulate radionuclides from reaching the environment, even under accident conditions.
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From page 34... ...
A review of the nuclear accidents at Three Mile Island and Chornoby1, see Chapter 4, illustrates how the design of reactors in the United States specifically addresses the nature of radioactive fission products and makes releases to the environment unlikely. In contrast, poor design of the Chornoby} reactor facility led to the release of a considerable portion of its entire fission-product inventory, including radioiodine.
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From page 35... ...
However, the inhalation-exposure route was not the major contributor to the thyroid doses of the populations exposed to radioiodine released in the Chornobyl accident; rather, as previously discussed, it was estimated that most of the radioiodine taken into the thyroid entered the body in contaminated food or drink. Evacuation and sheltering are the preferred methods of protecting populations from direct exposure to radioactive materials (including radioiodine)
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From page 36... ...
provided considerable information on reactor design, the types and quantities of radionuclides that can escape the nuclear fuel (source terms, environmental pathways and potential risks of released radionuclides to public health and safety. That accident was precipitated by an explosion and a fire in the graphite-moderated core.
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From page 37... ...
The breaching of the reactor building allowed the fire that consumed much of the reactor core to spew radionuclides, including radioiodine, directly to the atmosphere. In NPP licensing, the US Nuclear Regulatory Commission subscribes to the "defense-in depth" (multiple layers)
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From page 38... ...
Severe accidents cover the spectrum of releases involving life-threatening, environmental releases of large fractions of the available radioactive materials in a reactor (tens of millions of curies)
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From page 39... ...
In 1962, the Atomic Energy Commission adopted the analysis in Technical Information Document TID-14844 as the licensing model source term. This "hypothesized source term" was postulated to appear instantaneously in the containment atmosphere and to consist of 100°/O of the noble gases, 50°/O of the halogens (particularly radiolodine)
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From page 40... ...
Reactor-Accident Exposure Pathways In a reactor accident, there are three principal ways for radioactive materials to deliver radiation doses to people: external exposure to radiation emitted by radionuclides in the passing plume or from radionuclides deposited on surfaces, including the ground, internal exposure from inhalation of airborne radioactive material, and internal exposure from the ingestion of radioactively contaminated food or water. Absorption of radioactive material through the skin, either by direct absorption or absorption from contaminated wounds is
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From page 41... ...
To reduce exposure via the ingestion pathway, including thyroid exposure, officials would recommend that dairy animals be fed uncontaminated stored feed or recommend the interdiction of local milk supplies and contaminated foods (USNRC, 2002~. Other Types of Incidents Facilities that use radioactive iodine in research, medical diagnosis, and medical treatment and vehicles that transport the material could also be sources of exposure as a result of an incident.
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From page 42... ...
Less than IN of the radioactivity contained in a typical commercial NPP could be released from a naval reactor, and this limits the possible dose to the general public and the size of the area of potential concern. In addition, naval nuclear propulsion plants are ruggedly designed to withstand battle shock conditions, sit in an unlimited source of water that can be used for
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From page 43... ...
Base personnel are not considered the public in this situation just like employees at a reactor are not considered the public. However, significant thyroid doses at significant distances for the public located off the naval base are not likely if one takes into account all protective actions.
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