Inherently design safety

Inherently design safety features at facilities provides for adequate spacing, arrangement and segregation of equipment from high hazard to low hazard. The least hazardous process systems should be used for obtaining the desired product or production objectives. Protective systems are provided to minimized the effects that may occur from a catastrophic incident. 

Gas-cooled, graphite moderated reactors have several significant advantages over other reactor designs by virtue of their inherent passive safety characteristics. These are the result of the large thermal mass of the graphite core, the high... 

When designing a plant, every piece of process equipment should be specified as large enough to do its job, and no larger. We should minimize the size of all raw material and in-process intermediate storage tanks, and question the need for all in-process inventories, particularly of hazardous materials. Minimizing the size of equipment not only enhances inherent process safety, but it can often save money. 

Techniques such as adiabatic calorimetry (Dewar calorimetry) were by then well established [2, 118, 119]. All these techniques can be used for obtaining data to design for the prevention of runaway reactions, that is, to design for inherent plant safety. 

Keywords inherent safety, process plant design, safety analysis, case-based reasoning, genetic algorithm... 

Most petroleum and chemical facilities rely on inherent safety and control features of the process, inherent design arrangements of the facility, and process safety ESD features as the prime loss prevention measures. These features are immediately utilized at the time of an incident. Passive and active explosion and fire protection measures are applicable after the initiating event has occurred and an adverse affect to the operation has been realized. These features are used until their capability has been exhausted or the incident has been controlled. 

These are some of the numerous inherent design features that can be incorporated into the design of a process system depending on its nature. Not only should a process design achieve economic efficiency but the inherent safety of the process should be optimized simultaneously as well. 

Central venous catheters are reluctantly used as blood access for hemodialysis because of safety concerns and frequent complications, for example sepsis, thrombosis, and vessel stenosis. Nevertheless, 20% or more of all patients rely on atrial catheters for chronic dialysis because of lack of other access. Potentially fatal risks related to central venous catheters include air embolism (1), severe blood loss (2), and electric shock (3). These specific risks have been substantially eliminated by the inherent design and implantation of Dialock (Biolink Corporation, USA). Dialock is a subcutaneous device consisting of a titanium housing with two passages with integrated valves connected to two silicone catheters. The system is implanted subcutaneously below the clavicle. The tips of the catheters are placed in the right atrium. The port is accessed percutaneously with needle cannulas. 

Conceptual Design. During the conceptual design phase, the reaction pathway synthesis is undertaken the inherent process safety is incorporated the general... 

The situation is similar for the melter. The melter would contain over 100 kg of Pu and is not designed for inherent criticality safety with that mass amount. Also, the ventilation system was not designed for the possibility of Pu offgassing. Major redesign of the DWPF vessels and ventilation system would be required. 

To the second question, the failure of the human system, it is harder to give a definite answer, this being a matter more for the social sciences than the natural sciences. The matter was pursued over a wide range of operators, designers, safety experts, etc. The reader may feel able to reach the same conclusion as the Working Group that no inherent weakness has been identified but that the price of safety is continuous vigilance. The installation in UK nuclear power stations of extensive automatic equipment to protect the reactor plant from faulty actions by operators, and also the provision of plant protection under abnormal situations, is therefore to be welcomed. 

A. The material used to manufacture the flywheel of the reactor coolant pump motor will be produced by a commercially acceptable process that minimizes flaws, such as the vacuum melt and degassing process. This provides adequate fracture toughness properties under reactor operating conditions. The acceptance criteria for flywheel design will be compatible with the safety philosophy of the Pressure Vessel Research Committee (PVRC) of the Welding Research Council (WRC) primary coolant pressure boundary criteria as appropriate considering the inherent design and functional requirement differences between the pressure boundary and the flywheel. 

These characteristics enable the plant to operate with less need for routine operator intervention or presence. It is clear from this list that the safety of such small reactors relies much more on inherent design characteristics, and (to a lesser extent) on shutdown systems, than on engineered heat removal or prompt human intervention. 

Much of this fits into the employee right-to-know law. Part of designing safety into a system is ensuring that employees know which operations are inherently safe and which are not. This section should not only address that information but also detail what is considered good safety culture and how safety culture is central to the SMS (and everyone s business). This section also discusses the importance of formal safety awareness programs for the workplace, as well as how safety information is disseminated to all employees. 

For each of the mechanisms it is possible to find a number of provisions, such as inherent plant safety characteristics, safety margins, system design features and operational measures, which can support the performance of the SFs and prevent the mechanism from taking place. 

Accidents and mishaps are the direct result of hazards that have been actuated. (Note Accidents and mishaps are synonymous terms, and mishap has become the preferred term in system safety.) Mishaps happen because systems contain many inherent hazard sources (e.g., gasoline in an automobile), which cannot be eliminated since they are necessary for the objectives of the system. As systems increase in complexity, size, and technology, the inadvertent creation of system hazards is a natural consequence. Unless these hazards are controlled through design safety mechanisms, they will ultimately result in mishaps. 

System safety is a well-thought-out process that is planned, proactive, prudent, and preventive in nature. The primary objective of system safety is to avert mishaps by ensuring that safety is intentionally designed into a product or system. Designed-in safety leads to the inherent operational safety of a product or system. A system is considered safe when it presents acceptable mishap risk. Therefore, system safety is effectively a risk management process that deals in hazards and their associated mishap risk. 

Fig. 3.7 highlights the safety approaches taken generally by the VHTR, which relies on three inherent design features ... 

Reactor is safety shutdown and cooled by inherent design features without reliance on anv eauioment... 

Passive/inherent/safety-by-design safety systems, which do not require an operator or control system action ... 

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