Key Issues
Safety Benefits of Risk Assessment at U.S. Nuclear Power Plants
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There has been extensive research into the health effects of radiation. All people experience "background" radiation from naturally occurring sources, including the sun, the natural radioactivity of our bodies, and the earth. The typical background radiation level is about 300 millirem per year.
The normal operation of a nuclear plant contributes less than 1 millirem per year of additional radiation for individuals living near the plant. In comparison, people are exposed to about 1 millirem per year from watching television. Injury can occur only from very large radiation doses.
Combining the known information on radiation heath effects with the results of risk analysis, the risk of death for a resident near a nuclear plant is less than one-in-a-million per year. To put this in perspective, this is 25 times lower than the risk of being killed by a lightning strike and 12,000 times lower than the risk of dying in a car accident. Other forms of energy production, such as hydroelectric or fossil-fueled power stations, result in risk impacts higher than those of nuclear plants.
Risk assessment techniques provide a quantitative estimate of reactor safety and a basis for comparison to other risks we face. The most significant benefit of nuclear plant risk assessments is that they provide important insights that have led to safety improvements. These insights include:
For example, risk studies show that critical plant equipment that fails to operate or is out of service for maintenance could have an important impact on safety. This assessment led to a new NRC regulation requiring plants to monitor the performance of key equipment and optimize maintenance.
Risk studies also show that loss of power from outside the plant is a leading factor in accident probabilities. This led to a new NRC regulation requiring plants to improve procedures and equipment to assure backup power capability. In some cases, risk studies identified the need for design improvements at specific plants.
Insights from risk studies led to hundreds of individual plant equipment and procedure improvements by the industry. Risk study results demonstrated many opportunities for safety improvements, often from relatively simple plant changes.
There has been extensive research into the health effects of radiation. All people experience "background" radiation from naturally occurring sources, including the sun, the natural radioactivity of our bodies, and the earth. The typical background radiation level is about 300 millirem per year.
The normal operation of a nuclear plant contributes less than 1 millirem per year of additional radiation for individuals living near the plant. In comparison, people are exposed to about 1 millirem per year from watching television. Injury can occur only from very large radiation doses.
Combining the known information on radiation heath effects with the results of risk analysis, the risk of death for a resident near a nuclear plant is less than one-in-a-million per year. To put this in perspective, this is 25 times lower than the risk of being killed by a lightning strike and 12,000 times lower than the risk of dying in a car accident. Other forms of energy production, such as hydroelectric or fossil-fueled power stations, result in risk impacts higher than those of nuclear plants.
Risk assessment techniques provide a quantitative estimate of reactor safety and a basis for comparison to other risks we face. The most significant benefit of nuclear plant risk assessments is that they provide important insights that have led to safety improvements. These insights include:
- the most likely nuclear power plant events that could lead to an accident
- nuclear plant systems or equipment most important to avoiding or mitigating accidents
- operational practices important to avoiding or mitigating accidents.
For example, risk studies show that critical plant equipment that fails to operate or is out of service for maintenance could have an important impact on safety. This assessment led to a new NRC regulation requiring plants to monitor the performance of key equipment and optimize maintenance.
Risk studies also show that loss of power from outside the plant is a leading factor in accident probabilities. This led to a new NRC regulation requiring plants to improve procedures and equipment to assure backup power capability. In some cases, risk studies identified the need for design improvements at specific plants.
Insights from risk studies led to hundreds of individual plant equipment and procedure improvements by the industry. Risk study results demonstrated many opportunities for safety improvements, often from relatively simple plant changes.
