Which statement about LOPA is true?

• A. It is a method used to determine the entire plant design from scratch.
• B. It solely assesses maintenance costs.
• C. It estimates risk by evaluating independent protection layers and their capability to prevent or mitigate incidents; it helps determine required protection and whether existing layers suffice.
• D. It is a tool for personnel training only.

Answer: (C)

LOPA is a semi-quantitative risk assessment approach that looks at a specific hazard scenario and focuses on the protection already in place. It starts with an initiating event and then inventories independent protection layers (IPLs) that can prevent or mitigate the event if it occurs. Each IPL has a likelihood of failure on demand, and by considering how these layers work together, you estimate the residual risk and compare it to a risk target. If the remaining risk is higher than the target, you identify additional protection or stronger IPLs needed; if it’s below the target, the existing layers are considered sufficient.

That’s why this statement is the best: it captures the core use of LOPA—evaluating IPLs and their effectiveness to determine required protection and assess whether existing safeguards suffice. It’s not about designing an entire plant from scratch, nor about merely evaluating maintenance costs, nor is it a training-only tool.