Design inherently safe

Windhorst, J. C. A. (1995). Application of Inherently Safe Design Concepts, Fitness for Use and Risk Driven Design Process Safety Standards to an LPG Project."loss Prevention and Safety Promotion in the Process Industries, ed. J. J. Mewis, H. J. Pasman, and E. E. De Rademacker, 543-54. Amsterdam Elsevier Science B. V. 

T. Kletz, Process Plants A Handbook for Inherently Safe Design , Taylor Francis, London, 1998. 

The first step in approaching inherent safe design is to identify and understand basic thermodynamic data. A systematic approach to inherent safety, as outlined throughout this book, requires information concerning ... 

The global rates of heat generation and gas evolution must be known quite accurately for inherently safe design.. These rates depend on reaction kinetics, which are functions of variables such as temperature, reactant concentrations, reaction order, addition rates, catalyst concentrations, and mass transfer. The kinetics are often determined at different scales, e.g., during product development in laboratory tests in combination with chemical analysis or during pilot plant trials. These tests provide relevant information regarding requirements... 

Use an inherently safe design This basically means to use a low-pressure design where overpressure accidents would be minimal, but this... 

Under all circumstances, preference will be given to inherently safe design solutions. Safety systems should be designed to operate independent of any other functions and should operate reliably under all conditions determined by the risk analysis (including start-up, shutdown and maintenance and repair situations). 

The reactor is proposed to be modular, but with module sizes of 500 MW imits. This is chosen for convenience in sizing Brayton turbines, but is not small enough to constitute an inherently safe design as defined below. 

Clean technology is also about reducing the hazard and the risk both to people and the environment this brings in concepts such as inherently safe design of reactions and substitution of hazardous chemicals or those that pose a high risk. In short green chemistry is about reducing the environmental impact of both processes and products. 

The requirement here is to agree on the safety layers to be used and to allocate performance targets for the safety instrumented functions. In practice, safety functions are in many cases only allocated to safety instrumented systems where there are problems in using inherently safe designs or other technology systems. 

Inherently safe design. Eliminate or reduce risks as far as possible by construction. 

In process industry plants, the concept of more inherently safe design is a recurring theme in the three reports of the Advisory Committee on Major Hazards (ACMH - set up in the UK after the Flixborough accident). These reports set the general principles of new process industry safety in the UK and they represent in their field what, for example, the IAEA Safety Fundamentals documents do in the nuclear industry. 

Concerning the operability concept in the previous list of principles of more inherently safe design in the process industry, it seems worth noting that, in the parallel field of nuclear plants, designers tend now to provide a longer grace period in case of mistakes or accidents (e.g. an increase of the water inventory in water reactors, and so on). 

Elimination Substitution with noncorrosive or nonflammable materials, safe layout to prevent escalation Inherently safe design Plant design/operating procedure... 

When machine-related hazards. .. cannot be eliminated through inherently safe design, they must then be reduced to an acceptable level. 

Prevention of abnormal operation and failures Enhance prevention by increased emphasis on inherently safe design characteristics and passive safety features. 

Although safety controls can be added to existing processes, a more effective and efficient strategy is called inherently safe design [121. The idea is to streamline the process to eliminate hazards, even if there is a major process upset. This strategy is based on a hierarchy of six approaches to process plant... 

International Organization for Standardization (ISO) TC 184, Industrial Automation Systems and Integration ISO 10218-1 2006, Robots for industrial environments. Safety requirements. Parti Robot, Robotics Industries Association (RIA)—specifies requirements and guidelines for the inherent safe design, protective measures, and information for use of industrial robots describes basic hazards associated with robots and provides requirements to eliminate or adequately reduce the risks associated with these hazards. 

The thermal reactors at Windscale and those being huilt at Calder HaU are of an inherently safe design. With a fast reactor there is a conceivable cause of accident. This is one in which the coolant fails, the core melts and catches fire or in which the sodium (used for cooling) catches fire and subsequently fires uranium, volatilising and dispersing the fission products. 

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