Which two parameters are used to calculate risk in a PRA?

Which two parameters are used to calculate risk in a PRA?

• A. System reliability and human performance
• B. Annual radiation dose and exposure duration
• C. Maintenance downtime and cost
• D. Core damage frequency and large early release frequency

Answer: (D)

In PRA, risk is assessed by how often bad outcomes can occur and what their radiological impact would be. The two main numbers used are core damage frequency and large early release frequency. Core damage frequency estimates how often the reactor core sustains damage in a year, while large early release frequency estimates how often a substantial radiological release happens as a result of that damage. These two metrics directly quantify the most safety-significant events engineers worry about and let risk be expressed as a frequency of harmful outcomes that can be compared across designs or operating practices. Other options mix inputs (like system reliability or human performance) or refer to consequences (dose, exposure duration) or costs, which aren’t the primary frequency-based measures PRA uses to quantify risk.

In PRA, risk is assessed by how often bad outcomes can occur and what their radiological impact would be. The two main numbers used are core damage frequency and large early release frequency. Core damage frequency estimates how often the reactor core sustains damage in a year, while large early release frequency estimates how often a substantial radiological release happens as a result of that damage. These two metrics directly quantify the most safety-significant events engineers worry about and let risk be expressed as a frequency of harmful outcomes that can be compared across designs or operating practices. Other options mix inputs (like system reliability or human performance) or refer to consequences (dose, exposure duration) or costs, which aren’t the primary frequency-based measures PRA uses to quantify risk.