Documenting the Safety Control Structure

If STAMP has been used as the basis for previous safety activities, such as the original engineering process or the investigation and analysis of previous incidents and accidents, a model of the safety-control structure may already exist. If not, it must be created although it can be reused in the future. Chapters 12 and 13 provide information about the design of safety-control structures. 

The components of the structure as well as each component s responsibility with respect to enforcing the system safety constraints must be identified. Determining what these are (or what they should be) can start from system safety requirements. The following are some example system safety requirements that might be appropriate for the Citichem chemical plant example  

Chemicals must be stored in their safest form. 

The amount of toxic chemicals stored should be minimized. 

Release of toxic chemicals and contamination of the environment must be prevented. 

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T vo examples are used in this section one was a demonstration for NASA of risk analysis using STPA on a new management structure proposed after the Columbia accident. The second is pharmaceutical safety. The fundamental activities of identifying system hazards, safety requirements and constraints, and of documenting the safety control structure were described for these two examples in chapter 7. This section starts from that point and illustrates the actual risk analysis process. 

Document the safety control structure in place to control the hazard and enforce the safety constraints. This structure includes the roles and responsi-... 

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