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Introduction to Health Physics: Fourth Edition - Ruang Baca FMIPA UB

Introduction to Health Physics: Fourth Edition - Ruang Baca FMIPA UB

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SUMMARY<br />

Evaluation of Radiation Safety Measures 709<br />

If the activity were <strong>to</strong> be dispersed by an explosion, it could possibly (but<br />

unlikely) be life threatening <strong>to</strong> persons in the immediate vicinity. There would<br />

be little or no risk of immediate health effects <strong>to</strong> persons beyond a few hundred<br />

meters.<br />

Category 2—The sources falling in this category are personally very dangerous.<br />

Being close <strong>to</strong> the unshielded source for time periods of minutes <strong>to</strong> hours could<br />

cause permanent injury; and the exposure could be fatal for time periods of<br />

hours <strong>to</strong> days.<br />

Dispersed category 2 activity is very unlikely <strong>to</strong> be life threatening in the<br />

immediate vicinity of the bomb after the explosion. It would be virtually impossible<br />

for this source <strong>to</strong> contaminate a public water supply <strong>to</strong> a dangerous<br />

level.<br />

Category 3—The sources in this category are personally dangerous. Permanent<br />

injury may be caused following nearby exposure <strong>to</strong> the unshielded source for<br />

several hours; and could possibly (but unlikely) be fatal for a person who is close<br />

<strong>to</strong> the unshielded source for a period of days <strong>to</strong> weeks.<br />

The dispersed activity is extremely unlikely <strong>to</strong> permanently injure or kill a<br />

person in the immediate vicinity, and there exists little or no risk of immediate<br />

health effects beyond a few meters from the explosion.<br />

Category 4—The sources in this category are unlikely <strong>to</strong> be dangerous.<br />

The dispersed activity of a category 4 source would not permanently injure<br />

anyone.<br />

Category 5—The sources in this category are not dangerous. No one would<br />

be permanently injured either from the source or from the dispersed<br />

activity.<br />

Engineering and administrative measures are employed in order <strong>to</strong> provide a safe<br />

working environment for radiation workers. However, since there is no guarantee<br />

that protective measures will never break down, we keep the working environment<br />

and the workers under continuing surveillance <strong>to</strong> verify that all the protective systems<br />

are operating as designed. Should a breakdown occur, then the surveillance system<br />

should detect it in the early stages of the breakdown.<br />

The workplace is moni<strong>to</strong>red directly by two different methods: (1) by systematic<br />

and routine surveys that include measurement of external radiation, verification of<br />

the location and proper use of radiation sources, air sampling, and testing exposed<br />

surfaces for contamination, and (2) by fixed area moni<strong>to</strong>rs that continuously moni<strong>to</strong>r<br />

external radiation fields and airborne radioactivity and have alarms that are<br />

preset <strong>to</strong> warn of high levels of radiation or airborne radioactivity. Individuals are<br />

moni<strong>to</strong>red for external radiation with dosimeters, such as film badges, thermoluminescent<br />

dosimeters, and electronic dosimeters. For internally deposited radionuclides,<br />

workers are moni<strong>to</strong>red by in vitro bioassay, in which the activity in excreta<br />

is measured, or by in vivo bioassay, in which the radiations originating in radionuclides<br />

inside the body are measured directly with appropriate counting instruments.

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