Experiences operational

Operating plant experience benchmarks the adequacy of RPVt design and conservatism relative to operating conditions. The following observations of service performance of RPVIs important to safety are relevant to age related degradation. Age related degradation is the reduction in functional capability of a component as the result of phenomena that occur after a period of service and which may increase with time. 

A summary of degradation occurrences in RPVIs important to safety and the apparent cause is presented in TABLE 5-1. Other events could be read in reference [5.14]. 

To date, cracking of RPVIs has been limited to SCC and fatigue. Although degradation due to other mechanisms during plant life cannot be discounted, such occurrences would be expected to occur earlier in plant life. Field experience and the understanding of relevant degradation mechanisms support this conclusion. 

Orificed Fuel Support No incidents of cracking reported 

The inspections were performed by visual methods. Cracking in the core plate was observed in the rim near the welds of the rim to the plate after 19 on-line years of operation. GE subsequently issued SIL 588 [5.16], which updated their position regarding safety significance and provided specific recommendations for inspection. After review, the USNRC concluded that it was reasonable to expect future core plate ring and top guide cracking in U.S. BWRs [5.17]. 

Since her nuclear maiden run on October 11, 1968, the N.S. Otto Hahn has covered well over 170,000 nautical miles in more than 64 trial, research, and freight voyages between the Caribbean Sea and the Persian Gulf, the Arctic Circle and the Cape of Good Hope up to 

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The previous discussion demonstrates that measurement of precise isotope ratios requires a substantial amount of operator experience, particularly with samples that have not been examined previously. A choice of filament metal must be made, the preparation of the sample on the filament surface is important (particularly when activators are used), and the rate of evaporation (and therefore temperature control) may be crucial. Despite these challenges, this method of surface ionization is a useful technique for measuring precise isotope ratios for multiple isotopes. Other chapters in this book discuss practical details and applications. 

Several nontechnical factors can significantly affect the results of a nondestmctive inspection. Many of these are classified as human factors (1,2,17). Operator experience affects the probabiUty of detection of most flaws. Typically, an inexperienced operator has more false rejects, known as Type II errors, than an experienced operator. A poor operator has few false rejects but is more likely to miss a defect in the inspection, known as a Type I error. Operator fatigue, boredom, or an unfavorable environment such as lighting, cold, or rain may further affect performance. Thus it usually is a good investment for the inspection company to assure that the operator environment is most amenable to inspection, that the equipment is suitable for the task, and that the operator is alert and well rested. 

G. J. Raab md co-workers. Operating Experience Using Silver Reactors for Radioiodine Removal in the Hanford Purex Plant, ARH-SA-67, Atimtic Richfield Hmford Co., Richlmd, Wash., June 1970. 

R. L. Loftness, Nuclear Power Plants Design, Operating Experience and Economics, D. Van Nostrand Co. Inc., Princeton, N.J., 1964. 

D. Kitchen, A. Pinto, and H. Van-Praag, "ICI s Operating Experience with Shift Catalyst at Low Steam to Carbon Ratios," AIChE Ammonia Safety Symposium, Denver, Colo., Aug. 22—24, 1988, American Institute of Chemical Engineers, New York, 1989. 

Several utility-scale demonstration facilities having power outputs in the 300-MW class have been constmcted in the United States and Europe. These started accumulating operating experience in 1995 and 1996. Other IGCC plants have been constmcted, including units fueled by petroleum coke and refinery bottoms. Advanced 500-MW class IGCC plants based around the latest heavy-duty combustion turbines are expected to be priced competitively with new pulverized-coal-fined plants utilising scmbbers. 

In the past the successful operation of batch processes depended mainly on the skill and accumulated experience of the operator. This operating experience was difficult to codify in a form that enabled full use to be made of it in developing new designs. The gradual evolution of better instmmentation, followed by the installation of sequence control systems, has enabled much more process data to be recorded, permitting maintenance of process variations within the minimum possible limits. 

R. M. Heck, M. DudUa, A. G. Bouney, and J. M. Chen "Air Pollution Control—Ten Years Operating Experience with Commercial Catalyst Regeneration", paper presented at the 81st AECA Annual Meeting oA Exhibition, Dallas, Tex., June 19,1988. 

Operating experience (Wuestner et al., loc. cit.) has shown that roll diameters about 1 m are preferred, as a compromise between production rate and stress on the equipment. The press must be operated choke fed, with a substantial depth of feed in the hopper otherwise it will act like an ordinary roll crusher. 

Actual operating experience with full-scale plant equipment exposed to the corroding medium. 

Unit layout as installed is the next step of preparation. This may take some effort if analysts have not been involvea with the unit prior to the plant-performance analysis. The equipment in the plant should correspond to that shown on the PFDs and P IDs. Wmere differences are found, analysts must seek explanations. While a hne-by-line trace is not required, details of the equipment installation and condition must be understood. It is particularly useful to correlate the sample and measurement locations and the bypasses shown on the P IDs to those ac tuaUy piped in the unit. Gas vents and liquid (particularly water-phase) discharges may have been added to the unit based on operating experience out not shown on the P IDs. While these flows may ultimately be small within the context of plant-performance an ysis, they may have sufficient impact to alter conclusions regarding trace component flows, particularly those that have a tendency to build in a process. 

The operators have been given instructions on unit operation. Most of these are written and should have been studied prior to the meeting. Others may be verbal or implied. While this is not optimal, verbal instruc tions and operating experience are still part of every unit. It is not unusual that different shifts will have different operation methods. While none of the shift operations may be incorrect, they do lead to variability in operation and different performance. What-if ques-... 

Often, analysts will want to run special short-term tests with the operating unit in order to identify the cause of the trouble being experienced By the unit. Operators are naturally leery of running tests outside their normal operating experience because their primaiy focus is the stable control of the unit, and tests outside their experience may result in loss of control. Multiple tests with few results may decrease their cooperation. 

QRA practitioners can use to satisfy some QRA objectives. Also, the American Institute of Chemical Engineers (AIChE) has sponsored a project to expand and improve the quality of component failure data for chemical industry use. And many process facilities have considerable equipment operating experience in maintenance files, operating logs, and the minds of operators and maintenance personnel. These data can be collected and combined with industrywide data to help achieve reasonable QRA objectives. However, care must be exercised to select data most representative of your specific system from the wide range available from various sources. Even data from your own plant may have to be modified (sometimes by a factor of 10 or more) to reflect your plant s current operating environment and maintenance practices. 

A commercial combustion turbine with the provision to inject, at any point upstream of the combustor, the externally supplied humidified and preheated supplementary compressed air. Engineering and mechanical aspects of the air injection for the compressed air injection plant concepts are similar to the steam injection for the power augmentation, which has accumulated significant operating experience. 

Operating experience has proven that unless a continuous program of required lubrication is followed, even the most well-designed units are sure to fail. A proper lubrication management program must incorporate a monthly lubrication schedule, an evaluation of new lubrication products, and supervision to ensure the prescribed procedures are carried out by maintenance personnel. 

Packed columns are gaining ground on trayed columns. Lieberman states that based on his design and operating experience, a properly designed packed tower can have 20-40% more capacity than a trayed tower with an equal number of fractionation stages. 

Figure 9 shows the details of a typical horizontal tube-type ozone generator. This unit is preferred for larger systems. Water-cooled plate units are often used in smaller operations. However, these require considerably more floor space per unit of output than the tube-type units. The air-cooled Lowther plate type is a relatively new design. It has the potential for simplifying the use of ozone-generating equipment. However, it has had only limited operating experience in water treatment facilities. 

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