Risk Assessment: Tools, Techniques, and Their Applications

10.6 Use of Human Reliability Analysis Techniques for Analyzing Procedures

HRA techniques should be reserved for the most critical procedures. For instance, HRA should not be used for analyzing simple maintenance procedures because of the cost of performing the analysis. However, for critical operations, it is appropriate. Determining where recovery actions, such as inspection steps, should be in procedures is the best use of HRA techniques. Tools such as Tool for Human Error Analysis (THEA) (5) can be used for such analyses. The following analysis shows how HRA can be used to determine where recovery actions should be placed.

A modified coolant flush procedure will be used as the basis of the example. Procedure is listed as follows

10.6.1 Procedure

Warning: cooling system must be below 100°F prior to draining.

1. Begin with the engine cold and ignition off. Remove the radiator pressure cap.

Warning: ethylene glycol coolant is toxic and must be disposed of in an appropriate manner.

1. Open the petcock at the bottom of the radiator and drain the coolant into a bucket.

2. Close the petcock and fill the radiator with water.

3. Start the engine and turn the heater control to hot. Add cooling system cleaner and idle the engine for 30 min (or as per the instructions on container).

Warning:cooling system must be below 100°F prior to draining.

1. Stop the engine and allow it to cool for 5 min. Drain the system.

2. Close the petcock, fill the radiator with water and let the engine ...