Risk assessment process identifying significant hazards

The next step in the risk assessment process is to identify accident scenarios and develop the initiating events for those scenarios. A hazard analysis was performed and various hazards were identified. Of the hazards identified, the most significant were related to the uncontrolled release of cryogenic fluid or gas. With that information, a fault tree was constructed for the system with the top event designated as uncontrolled cryogenic release. An FMEA was performed on those components that were determined to be critical to the fault tree. 

A similar application of ecotoxicological data is hazard assessment. Unlike risk assessment, hazard assessment is nonprobabilistic and relies upon indices rather than probabilities. One such index is the hazard quotient , which is the ratio of the expected environmental concentration (based upon field surveys or simulation models) divided by a benchmark concentration. The benchmark concentration is derived from some measure of toxicity such as the LC50 or no-observed-effect level. Hazard assessments are often conducted at different levels or tiers of increasing complexity and specificity if a chemical is identified as potentially hazardous by tier (the least complex and specific test), a decision is made to take action or, if more information is needed, to proceed to tier 2 tests. After tier 2 tests, a decision is made whether to take action or proceed to tier 3 tests, and so on. This process is repeated until it is decided that there is enough information to determine whether or not there is significant ecological hazard. If there is, then regulatory action is taken. 

RISK EVALUATION is the second subdivision of Risk Assessment and is the complex process of determining the significance or value of the identified hazards and estimated risks to those concerned with or affected by the decision. 

The risk assessment must be maintained. This means that any significant change to a workplace, process or activity, or the introduction of any new process, activity or operation, should be subject to risk assessment. If new hazards come to light, then these should also be subject to risk assessment. The risk assessment should in any case be periodically reviewed and updated. This is best achieved by a suitable combination of safety inspection and monitoring techniques, which require corrective and/or additional action where the need is identified. Typical monitoring systems include ... 

Where the relevant safety requirements can be complied with, the Hazard Consequence Report continues to be processed in a nominal manner. If, for some reason, a defined safety requirement cannot be satisfactorily implemented, or its implementation cannot be verified as complying with the intent of the requirement, then once again the relevant report is identified as potentially unresolved. Furthermore, if risk assessment determines that, in spite of compliance with defined requirements, significant risk contributors remain in the design, then the relevant report is also identified as potentially unresolved. At this stage, additional safety critical items may also be identified. 

Process Hazard Analysis— An organized effort to identify and evaluate hazards associated with chemical processes and operations to enable their control. This review normally involves the use of qualitative techniques to identify and assess the significance of hazards. Conclusions and appropriate recommendations are developed. Occasionally, quantitative methods are used to help prioritize risk reduction measures. 

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