BACK TO BASICS
Do you know anyone who ' d like to learn a bit more about radiation protection ? This cut-out sheet will help .
What is Radiation Protection ?
Radiation protection is the protection of people and other organisms from the harmful effects of ionising radiation .
Where does Radiation Exposure come from ? Radiation exposure may come from sources outside the body ( external exposure ) or from radioactive materials which get into the body ( internal exposure ), for example through radioactive material being breathed in or eaten .
Reducing External Radiation Exposure This is done via combinations and variations of three basic parameters :
• Time of exposure
• Distance from the source of radiation
• Shielding to reduce radiation intensity
Time Dose = Dose rate x time The longer the exposure to a source of radiation , the higher the dose received . The amount of time a person spends working with radiation is carefully monitored , and minimised wherever possible .
Distance The rate of external radiation exposure reduces with distance . For point sources of radiation , the Inverse Square Law applies . Therefore if you increase the distance from the source , the radiation dose rate at the place of exposure is reduced .
Inverse Square Law Dose rate is reduced by the square of the distance . For example if you double the distance
2 the dose rate reduces by a factor of 4 ( 2 ).
What is a key principle of Radiation Protection ? To keep doses As Low As Reasonably Practicable ( ALARP ).
Reducing Internal Radiation Exposure This is controlled by preventing radioactive materials from getting inside the body . This is done either by containing radioactive materials so they cannot be dispersed in the environment as radioactive contamination , or by using protective clothing , respiratory protection and personal hygiene .
Time
Distance
Shielding
Shielding Different types of radiation and their penetration capabilities determine shielding types .
• Alpha radiation can be stopped by the outer layer of skin or paper , so is not an external radiation hazard .
• Beta radiation can be stopped by 1cm of acrylic or a thin layer of metal and is usually only a hazard to the skin .
• Gamma radiation is more penetrating and needs dense materials like lead or thick concrete to reduce radiation exposures to acceptable levels .
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36 Radiation Protection Today www . srp-rpt . uk