System safety energy analysis

A Brief Overview of Selected System Safety Analytical Approaches Working with the Risk Assessment Matrix Preliminary Hazard Analysis Energy Flow/Barrier Analysis Failure Modes and Effects Analysis Fault Tree Analysis... 

Guimares, A. C. F. Lapa C. M. F. 2004. Fuzzy FMEA Applied to Pwr Chemical and Volume Control System. Progress in Nuclear Energy 44 N. 3 191—213, 2004. Pillay, A. Wang, J. 2003. Modified failure mode and effects analysis using approximate reasoning. Reliability Engineering and System Safety 79 69-85. 

A typical system safety task for hazard identification would be the preparation of a preliminary hazard list (PHL). Hazard identification or discovery is accomplished by reviewing lessons learned, accident reports, and other historical data. A PHL may be prepared through an informal conference, the use of checklists, and occasionally other techniques such as energy trace and barrier analysis (ETBA). 

Low-risk facilities are those with low energy levels and those with which the COE has a considerable amount of trouble-free experience, such as basic administrative buildings and housing. The system safety effort for these facilities may consist primarily of the PHL, with no additional analysis required. 

In contrast, the Department of Energy s MORT-based approach provides excellent accident investigation, audit, and appraisal tools oriented to ongoing operations. Despite emphasis on the importance of the upstream process, however, system safety programs based on MORT tend to lack the early, detailed, systematic hazard identification and analysis efforts that are characteristic of MIL-STD-882B programs. 

Change analysis is one of the techniques associated with the Department of Energy s management oversight and risk tree (MORT) approach to system safety. Unlike the MORT chart itself or some of the other tools and techniques associated with the MORT program, change analysis is a very simple, straightforward process that is relatively quick and easy to learn and to apply. 

An example of how change analysis can be used to find an obscure direct cause relatively quickly is contained in a story frequently told by instructors from the Department of Energy s System Safety Development nter. 

The basic concept from which event and causal factors charts were developed can probably be traced back to Ludwig Benner and others at the National Transportation Safety Board. Benner developed a very similar technique called multilinear event sequencing (MES) and more recently sequentially timed events plotting (STEP). Event and causal factors charts were part of the overall MORT approach to system safety developed by W. G. Johnson for the Atomic Energy Commission in the early 1970s and further developed and taught by the Department of Energy s System Safety Development Center (SSDC). The use of the event and causal factors chart is sometimes referred to as causal factors analysis. 

Sometimes referred to as energy flow analysis, HazOps is used primarily in the petrochemical industry. It uses a multidisciplinary team similar to a system safety working group for the systematic review of the flow of materials through a process. It concentrates on key locations in the process known as study nodes and uses a series of guide words and parameters to examine possible deviations and the causes and consequences of deviations (Goidwaite 1985). 

While the OSHA rule applies to operations that affect workers within a site where certain highly hazardous chemicals are present at stated levels, the EPA rule was developed to additionally protect the public and the environment from the undesired consequences of explosions and other accidental releases. Much of the information in this chapter comes from DOE-STD-1100 (U.S. Department of Energy 19%) and is enhanced with associated material from the System Safety Analysis Handbook (Stephans and Talso 1997) and other sources as specified. 

The ETBA is one of the fundamental tools of system safety analysis and, when used, can not only document the adequacy of hazard barriers and controls but also identify those energy flow areas within a system that may have been overlooked as potential risk hazards during the concept or design phase of the project. 

As the practice of system safety moves into its seventh decade of existence, special use analysis methods and techniques have been developed as a result of the steady increase in system complexity and acceleration in technological advancements. These changes have brought with them new concerns over the adequacy of existing hazard reduction and control techniques. Automated systems that incorporate complicated data and energy flow transfer paths, as well as those whose correct operation... 

Blackmane, H. S., D. I. Gertman, and L. N. Haney (Sept. 1985). The Process of Task Analysis (SSDC-31), U.S. Department of Energy, System Safety Development Center, EG G Idaho, Inc., Idaho Falls. 

Exergy analysis can be used to compare FP-FC systems with rechargeable batteries and combustion engines. Other important aspects, in addition to exergetic efficiency, are environmental impact, safety and life cycle cost. Efficient fuel utilization is particularly important for larger FP-FC systems. For small systems, the energy... 

Energy Trace and Barrier Analysis A system safety analytical technique used to evaluate the flow of energy through a system and analyze the effectiveness of existing barriers within the system which are intended to prevent unwanted transfers of that energy flow. 

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