Safety systems engineering scope

The NPRDS is an industry-wide system for monitoring the performance of selected systems and components at U.S. commercial nuclear power plants. Information in NPRDS is derived from a standardized format input report prepared by U.S. nuclear plant licensees. The plants are as)ced to submit failure reports on catastrophic events and degraded failures within the defined reportable scope reporting of incipient events is optional. Command faults are not reportable unless they malce an entire system unavailable. In addition, the plants are as)ced to file component engineering reports on all components within the selected systems and reportable scope. These reports contain detailed design data, operating characteristics, and performance data on the selected systems and components (over 3000 components, from approximately 30 systems, per unit). The selected systems are primarily safety systems. 

As already mentioned, the scope and depth of the analyses may differ. If only the left-hand side of the bow-tie diagram is treated, we are dealing with a probabilistic safety analysis. Its results are the expected frequencies of undesired events. The objectives then are to identify weak points and imbalances in the engineered safety systems as weU as to indicate ways for eliminating them. This is the most work-intensive part of a risk analysis. 

Previous discussions here on safety requirements have indicated that the scope of system safety analyses must address the system, service and operational environment. This vast scope presents a challenge for the systems engineer who needs to consider the safety-related aspects of the entire system and then to focus the often limited resources available on the most critical system functions. 

The book does not focus on occupational safety and health issues, although improved process safety can benefit these areas. Detailed engineering designs are outside the scope of this work. This book intends to identify issues and concerns in batch reaction systems and provide potential solutions to address these concerns. This should be of value to process design engineers, operators, maintenance personnel, as well as members of process hazards analysis teams. While this book offers potential solutions to specific issues/concerns, ultimately the user needs to make the case for the solutions that provide a balance between 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. 

Safety instrumented system audits provide beneficial information to plant management, instrument maintenance engineers and instrument design engineers. This enables management to be proactive and aware of the degree of implementation and effectiveness of their safety instrumented systems. Many types of audits, which can be carried out exist. The actual type, scope, and frequency of the audit of any specific activity should reflect the potential impact of the activity on the safety integrity. 

In MORT Safety Assurance Systems by WilMam G. Johnson, the chapter on The Safety Function also quotes the ASSE Scope and Functions of the Professional Safety Position (p. 463). Introduction to Safety Engineering by David S. Gloss and Miriam Gayle Wardle contains the only reference I found in a safety-related text that speaks of the requirements of a profession. This is what they wrote. 

This is not a finite listing, as other, more complex approaches such as Managanent Oversight and Risk Tree Analysis (MORT), failure mode and effect analysis, and the aspects of system safety engineering are not covered within the scope of this book. These approaches can be found in many other books and articles. 

Condensed adaptations of material from that publication appear here, with the permission of SEMATECH. There are similarities between this system and the one issued by the automobile manufacturing industry. However, the scope of the severity criteria encompasses all forms of harm, damage, or loss. Also, the value of counsel available from safety engineering personnel is recognized by including that designation—safety engineerings—in the job titles of personnel who would form a team to conduct FMEAs. 

A first approach of cybernetics to the safety complex of a technical system is the frequent utilization of control circuits in order to keep the behavior of a machine on a predetermined path. The selection of the technical methods meant to achieve safety is the task of safety engineering and not the science of safety. The latter has a far greater scope. 

In MORT Safety Assurance Systems, William G. Johnson (1980) includes a chapter titled The Safety Function. It commences with these questions. What is the nature of the safety function What are the safety professional s responsibilities, qualifications, and methods. This 1980 publication pleads for answers to those questions. Johnson quotes from Scope and Functions of the Professional Safety Position published by the American Society of Safety Engineers (1998) as a reference paper (463). 

The scope of this research includes engineering safety analysis and management that is applicable to any industry, but with the trial implementation being specific to the railway industry. The methodology aims to support the systems safety analysis and the identification of major contributors to safety risks and benefits, whilst safety and business decision-making is supported through the evaluation of different... 

This standard sets out practices in the engineering of systems that ensure an industrial process s safety through the application of instrumentation. The scope of lEC 61511 includes the following items [19,20] ... 

Step 7 Final safety assessment of the plant and evaluation of the probability failure of the structures, systems and components that have been categorized for external events are based on the actual hazard and design methodologies used in the design/qualification (box (10) of Fig. 1). This step aims at fine tuning the engineering safety features to ensure that any structure, system or component can provide the required safety function with the required reliability (Section 4). This step replaces a full scope PSA with simplified probabilistic methodologies. 

In June 1966, MIL-S-38130 was revised. Revision A to the specification once again expanded the scope of the SSP by adding a system modernization and retrofit phase to the defined life-cycle phases. This revision further refined the objectives of an SSP by introducing the concept of maximum safety consistent with operational requirements. On the engineering side, MIL-S-38130A also added another safety analysis the Gross Hazard Study (now known as the Preliminary Hazard Analysis). This comprehensive qualitative hazard analysis was an attempt to focus attention on hazards and safety requirements early in... 

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