Final answer:
The maximum permissible dose of radiation in an unrestricted area is 1 mSv per year. Additional radiation exposure, such as an extra 0.05 mSv, can increase the risk of cancer, with calculations based on population and radiation dose rates. The risk from occupational exposures, like those at nuclear power plants, are managed with specific safety guidelines.
Step-by-step explanation:
Permissible Radiation Dose in Unrestricted Areas
In an unrestricted area, the maximum permissible dose of radiation is 1 mSv per year. This limit is set to protect the general public from the effects of exposure to ionizing radiation. For occupational exposures, such as for workers in nuclear power plants, the limits are higher due to the nature of their work and the safety protocols in place.
Calculations Based on Additional Radiation Exposure
If everyone in Australia received an extra 0.05 mSv per year of radiation, the increase in the number of cancer deaths per year can be calculated using the provided rate of 200 × 10-4 deaths per Sv of radiation per year. To find the overall risk, one must convert mSv to Sv and then multiply by the population of Australia and the given death rate.
Example of an effective dose calculation:
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- Thyroid: 0.04 X 1 (mSv)
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- Brain: 0.01 X 1 (mSv)
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- Salivary gland: 0.01 X 1 (mSv)
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- Bone marrow: 0.12 x 1 (mSv) x 0.1
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- Skin: 0.01 X 1 (mSv) × 0.15
Totaling these contributions gives us an effective dose of 0.07 mSv.
Radiation-Induced Risks
The yearly risk of death from cancer and the chance of genetic defect due to a given dose of radiation can be assessed using the linear hypothesis, which assumes that risk is proportional to dose. For more substantial exposures, such as a plumber at a nuclear power plant receiving 30 mSv, specialized calculations based on dose and exposure rates are required to estimate risk.