Mitigation effectiveness, examples

The team suggested mitigations. For example, the consequences of an ammonia release could be markedly reduced by a reliable and quick-acting water spray system. The probability of damage due to ship collisions could be reduced by a f tor of five by a speed limit of eight knots. Evacuation of the potentially affected is practicable and effective. 

The release of radiological materials in any specific accident scenario is usually less than the total inventory present, depending on the postulated confinement barrier failure in the DBA and the limitations to release Inherent In the physical form of the hazardous material. The source term released by initial confinement barrier failure may be reduced even further by mitigative effects which occur during transport or leakage from the facility to the environment. For example, filtration in the ventilation system will normally trap a large fraction of the fission products but would still allow the volatile noble gas fission products to be released from the HCF stack. 

In addition, just as employee participation is the key element of process safety management systems, worker involvement is crucial to the effective application of Safety Cases. Unfortunately, the perception among many that a Safety Case is a lengthy, highly technical document that can only be understood by specialists, mitigates effective employee participation. For example the Computational Fluid Dynamics (CFD) technique used to model explosion over-pressure uses very sophisticated mathematics. This sophistication makes communication with nonspecialists a challenge. In addition the sheer size and complexity of a Safety Case may serve as a barrier to the involvement of nontechnical personnel. 

Vanadium phosphoms oxide-based catalysts ate unstable in that they tend to lose phosphoms over time at reaction temperatures. Hot spots in fixed-bed reactors tend to accelerate this loss of phosphoms. This loss of phosphoms also produces a decrease in selectivity (70,136). Many steps have been taken, however, to aHeviate these problems and create an environment where the catalyst can operate at lower temperatures. For example, volatile organophosphoms compounds are fed to the reactor to mitigate the problem of phosphoms loss by the catalyst (137). The phosphoms feed also has the effect of controlling catalyst activity and thus improving catalyst selectivity in the reactor. The catalyst pack in the reactor may be stratified with an inert material (138,139). Stratification has the effect of reducing the extent of reaction pet unit volume and thus reducing the observed catalyst temperature (hot... 

All efforts to prevent or correct LAQ problems should include an effort to identify and control pollutant sources. Source control is generally the most cost effective approach to mitigating LAQ problems in which point sources of contaminants can be identified. In the case of a strong source, source control may be the only solution that will work. The following are categories and examples of source control ... 

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