Design process acceptable risk

Most of these methods are commonly employed in the downstream processing of the desired ceU culture technology product. Hence, most of the time it is only necessary to demonstrate that the designed process is reducing the putative risk factors to acceptable levels. Validation methods employed for risk reduction are discussed in the Hterature (25). 

Validation starts with good process design, which permits reduction of the risk factors to an acceptable level. Once the process is well characterized it can be validated. It is essential to know where in the process the risk factors are removed and how much risk will be incurred if a manufacturing deviation occurs. Process validation provides such information. 

Process Design from the Assessed Hazards and Achieving an Acceptable Risk... 

The first step in the acceptance process is the identification of the environment within which the pre-developed software will have to work. This environment is determined by the system-level safety function as described in the system requirements specification. Also the interface and performance requirements, as well as the safety category should be contained in the system requirements specification. This means, that during the establishment of the plant safety design base a risk and hazards analysis has been performed which rendered the categories of safety functions to be implemented by pre-developed software. This risk and hazard analysis - in spite of being out of the scope of I C engineering - has been taken as the first of four acceptance criteria that should be applied to pre-developed software independently of its safety category. 

Requirements to achieve an acceptable risk level in the design process can usually be met without great cost if the decision-making takes place sufficiently upstream. When that does not occur, and retrofitting to eliminate or control hazards is proposed, the cost may be so great as to be prohibitive. 

To repeat the previous quote from ISO/IEC Guide 51, There can be no absolute safety some risk will remain, defined in this Guide as residual risk. In the real world, attaining zero risk, whether in the design process or in operations, is not possible. Nevertheless, the residual risk, after risk avoidance, elimination, or control measures are taken, should be acceptable, as judged by the decision makers. 

In the six years since the second edition of On the Practice of Safety was published, several developments have taken place that require or propose that hazards be recognized and analyzed in the design process and that risk assessments be made toward achieving an acceptable risk level. Safety practitioners—pay attention. Comments on some of those developments follow. 

Guidelines issued by the semiconductor industry provide another indication of a trade association having recognized the value of hazard analysis and risk assessments in the design process to eliminate or control hazards and to attain acceptable risk levels. To do what the issued guidelines propose requires that manufacturers have persoimel on their staffs who are skilled in hazard analysis and risk assessment. 

From the very beginning, the top priority is that hazards are to be eliminated in the design process. If an identified hazard cannot be eliminated, the associated risk is to be reduced to an acceptable level through design decisions. 

What-lf Hazard Analysis. This hazard assessment method utilizes a series of questions focused on equipment, processes, materials, and operator capabilities and limitations, including possible operator failures, to determine that the system is designed to a level of acceptable risk. Users of the What-If method would identify possible unwanted energy releases or exposures to hazardous environments. Bulletin 135 contains procedures for use of a What-If checklist. For some hazards, a What-If checklist will be inadequate and other hazard analysis methods may be used. 

To be in a position to anticipate hazards, one must be involved in the design process. To effectively participate in the design process, the safety professional must be skilled in hazard analysis and risk assessment techniques. Influencing the design process and using hazard analysis and risk assessment techniques to achieve acceptable risk levels are the bases upon which system safety is built. 

Subsystem-level reviews should be completed by the enterprise for each subsystem after completion of component reviews associated with the subsystem. This review is to determine whether the subsystem detailed design satisfies the design-to baseline risks are mitigated and remaining risks are acceptable issnes for all components, assemblies, and life cycle processes are resolved and accomplishments and plans warrant continuation with FAIT. 

This Technical Report is an excellent resource for safety professionals who want to understand how the lean process and safety principles can be melded to serve waste reduction purposes while maintaining acceptable risk levels. It provides guidance from the initial concept stage for design and redesign and addresses operational waste reduction applications. 

The goal to be achieved in the design and redesign processes is acceptable risk levels. 

A convincing statement is made, as in the following excerpt, about the need, sometimes, to go beyond issued safety standards in the design process and to have decisions on acceptable risk levels be based on risk assessments. This excerpt is taken from Related Information 1— Equipment/Product Safety Program, which is an adjunct to SEMI S2-0706, Environmental, Health, and Safety Guideline for Semiconductor Manufacturing Equipment. 

Since it is well established that the most effective and economic method of achieving and maintaining acceptable risk levels it to address hazards and risks in the design and redesign processes, prevention through design must be given prominence in a systemic causation model. 

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