Fire, preliminary hazard analysis

Several qualitative approaches can be used to identify hazardous reaction scenarios, including process hazard analysis, checklists, chemical interaction matrices, and an experience-based review. CCPS (1995a p. 176) describes nine hazard evaluation procedures that can be used to identify hazardous reaction scenarios-checklists, Dow fire and explosion indices, preliminary hazard analysis, what-if analysis, failure modes and effects analysis (FMEA), HAZOP study, fault tree analysis, human error analysis, and quantitative risk analysis. 

For example, from a safety perspective someone needs to compute the water supply requirements for fire protection and other uses. Someone needs to identify which spaces or operations need emergency lighting or power. A safety specialist may need to conduct a preliminary hazard analysis or other analysis for some or all operations or spaces. The results will give the design team information to incorporate into the design. 

Table 21.7.2 smnmarizes die results of applicadon of a preliminary liazard analysis (PHA) to the pyrolysis section of an ediylene plant. The major liazard to the persomiel and plant is die fire or explosion hazard of die gases used or produced in die process. 

The techniques used to complete PHAs inelude What-iF analyses. Explosive Safety Checklist Analyses, General Industry Checklist analyses and FMEA analyses. The information from Preliminary Hazards Analyses, previous Final Safety Analysis Report analyses. Fire Hazards Analyses, and other... 

First, the importance of learning lessons from past process safety incidents is highlighted in Section 3.2. The subsequent section presents preliminary hazard review procedure, risk matrix, what-if method, plot plan and layout review, pressure relief system review and fire safety design aspects. Section 3.4 presents PHA techniques and procedures hazards and operability analysis (HAZOP), failure modes and effects analysis (FMEA), instrumented protective system (IPS) design, fault trees, event trees, layer of protection analysis (LOPA) and finally SIS life eyele. The importanee of revision of PSI is highlighted in Seetion 3.5. 

A formal hazard analysis of the anticipated operations was conducted using Preliminary Hazard Assessment (PHA) and Failure Modes and Effects Analysis (FMEA) techniques to evaluate potential hazards associated with processing operations, waste handling and storage, quality control activities, and maintenance. This process included the identification of various features to control or mitigate the identified hazards. Based on the hazard analysis, a more limited set of accident scenarios was selected for quantitative evaiuation, which bound the risks to the public. These scenarios included radioactive material spills and fires and considered the effects of equipment failure, human error, and the potential effects of natural phenomena and other external events. The hazard analysis process led to the selection of eight design basis accidents (DBA s), which are summarized in Table E.4-1. 

Potential external events were identified by reviewing previous Safety Analysis Reports of similar DOE facilities (Restrepo 1995) and the recommended list of external events used to evaluate commercial nuclear power plant risks (NRC 1983). In addition, an attempt was made to identify any other potential external-initiating event unique to the site that had not been considered in previous studies. It is important to note that operational accidents (e.g., criticality, internal fires) occurring inside the HCF and assodated radioactive material storage facilities are not considered in this screening process. These types of "internal initiating events are identified separately using preliminary hazard checklists (see Appendix 3A). 

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