Safety plant design

SAKHA-92 is a maintenance-free nuclear power plant of increased safety. Plant design was developed on the basis of PWR technology, but implements integrated steam and gas pressurizer systems and relies on natural circulation of the primary coolant (Fig. 1). The use of such designs as leak-tight turbine-generator, canned condensate and feed pumps allows to secure the tightness of both primary and secondary circuits, which in turn make it possible to exclude some auxiliary systems. 

T. Kletz, Plant Design for Safety, A UserFriendly Approach, Hemisphere Publishing, New York, 1991. 

T. A. Klet2, Plant Design for Safety A Eser-Friendly Approach, Hemisphere Publishing Co., London, 1991. 

Nuclear Reactors. Nuclear power faciUties account for about 20% of the power generated in the United States. Although no new plants are plaimed in the United States, many other countries, particularly those that would otherwise rely heavily on imported fuel, continue to increase their nuclear plant generation capacity. Many industry observers predict that nuclear power may become more attractive in future years as the price of fossil fuels continues to rise and environmental regulations become more stringent. In addition, advanced passive-safety reactor designs may help allay concerns over potential safety issues. 

For many years the usual procedure in plant design was to identify the hazards, by one of the systematic techniques described later or by waiting until an accident occurred, and then add on protec tive equipment to control future accidents or protect people from their consequences. This protective equipment is often complex and expensive and requires regular testing and maintenance. It often interferes with the smooth operation of the plant and is sometimes bypassed. Gradually the industry came to resize that, whenever possible, one should design user-friendly plants which can withstand human error and equipment failure without serious effects on safety (and output and emciency). When we handle flammable, explosive, toxic, or corrosive materials we can tolerate only very low failure rates, of people and equipment—rates which it may be impossible or impracticable to achieve consistently for long periods of time. 

Improving the economics of gas plant design, construction, and operations is essential to ensure the approval of future de-bottlenecking, capacity expansion, and new projects. The economics include not only capital investment, life cycle operations, and maintenance costs, but also the monetary equivalents of safety, reliability, and availability. 

It is hoped that this volume will provide some guidance to operators, plant safety engineers and designers, and that some of the design practices are adopted particularly in older plant operations that do not apply proper pressure let down procedures and flaring practices. Many unsafe operations and even catastrophic failures have been observed by the author in overseas assignments to such countries as Ukraine and other Newly Independent States (NIS) in older plant designs. These incidents have prompted the preparation of this reference. 

Wells, G. L., Safety in Process Plant Design, John Wiley Sons, New York, 1980. 

Humans require time to react to process alarms and control requirements. Reaction time must always be considered early in the plant design. It is inherently safer to decide early in process design what administrative controls the operator will be assigned to activate for safety control. Requiring periodic operator interface to the process system relieves boredom and heightens interest in knowing the current condition of the process. See Sections 6.4 and 6.5. 

Kletz, T. A. (1991b). Plant Design for Safety. New York Hemisphere. 

Lutz, W. K. (1995a). Take Chemistry and Physics into Consideration in All Phases of Chemical Plant Design. Process Safety Progress 14, 3 (July), 153-62. 

Lutz, W. K. (1995b). Putting Safety into Chemical Plant Design. Chemical Health and Safety 2, 6 (November/December), 12-15. 

Rogers, R. L., D. P. Mansfield, Y. Malmen, R. D. Turney, and M. Verwoerd (1995). The INSIDE Project Integrating Inherent Safety in Chemical Process Development and Plant Design. International Symposium on Runaway Reactions and Pressure Relief Design, August 2-4, 1995, Boston, MA, ed. G. A. Melhem and H. G. Fisher, 668-689. New York American Institute of Chemical Engineers. 

Snyder, P. G. (1996). Inherently Safe(r) Plant Design. Process Plant Safety Symposium, Volume 1, April 1-2,1996, Houston, TX, ed. H. Cullingford, 203-215. Houston, TX South Texas Section of the American Institute of Chemical Engineers. 

The confluence of sharply rising Operations and Maintenance (O M) costs. NRC requested Individual Plant Examinations (IPEs) and increased personal computer capabilities gave rise to the R R Workstation. Its uses and maintains-current PSA models and databases for individual plants to perform O M planning and scheduling, and uses the PSA in IPE models to identify plant design, procedure and operational vulnerabilities. The Risk and Reliability Workstation Alliance was organized by EPRI to support the R R Workshop in order to achieve O M cost reduction, plant productivity and safety enhancement through risk-based, user-friendly, windowed software louls (Table 3.6 8). The Alliance, initiated in 1992, includes 25 U.S. utilities and four international partners from Spain, France, Korea, and Mexico. SAIC is the prime contractor for the R R Workstation, with participation of five other PSA vendors. 

Two studies resolved the Unresolved Safety Issue A-44, "Station Blackout." The first siudy, The Reliability of Emergency AC Power Systems in Nuclear Power Plants," when combined uh die lelevant loss-oToffsite-power frequency, provides estimates of station-blackout frequencies lor 18 nuclear power plants and 10 generic designs. The study also identified the design and operational features most important to the reliability of AC power systems. The second study, "Station Blackout Accident Analysis" (NUREG/CR-3226), focused on the relative importance to risk of laiion blackout events and the plant design and operational features that would reduce this risk. 

My book Plant Design for Safety—A User-Friendly Approach [1] and References 12-15 describe many examples of ways in which plants can be made inherently safer. Note that we use the term inherently safer, not inherently safe, as we cannot avoid every hazard. 

Provision for protection and safety equipment should be incorporated in the original plant design. The size of the plant, nature of the hazards, and the e.xposure will determine the amount, kind, and location of this equipment. 

C. R. Burklin, "Safety Standards, Codes and Practices for Plant Design, Client. Eng., 79, 56-63, October 2, 1972. 

The first step in minimizing accidents in a chemical phuit is to evaluate the facility for potential fires, explosions, and vulnerability to other liazards, particularly those of a chemical miture. This calls for a detailed study of plant site and layout, materials, processes, operations, equipment, and training, plus an effective loss prevention program. The technical nature of industry requires detailed data and a broad range of experience. Tliis complex task, today becoming the most important in plant design, is facilitated by the safety codes, standiu ds, and practice information available. The technical approach to evaluating die consequences of hazards is discussed later in tliis cliapter and in Part V (Chapters 20 and 21). 

Occupational Safety and Health Administration regulations as they relate to (a) safety of design related to injury to personnel (includes such matters as latest vessel design [53], noise level from operating equipment, etc., [20, 21, 22, 23, 24, 25, 26, 27, 28]. (b) safety of the plant layout emdronment which might influence the safety of the plant facilities. 

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