Safe operation

Main steamline section and weld of the same Unit 4 f600 MW3 as above the weld connects 2 steamline sections of different materials (stainless steel and low-alloy steel) through a transition material section, ahead of the Y-piece where branching of the turbine inlet lines takes place (255 mm internal diameter, 44.5 mm thickness). Ultrasonic inspection pointed out potential integrity problems in the weld. The requirement was again that AE could support safe operation of the weld until the next incoming planned maintenance shutdown. 

This header has undergone repair after through-thickness cracking of an assembly weld after 108.000 hours of service, it is presently in operation and periodically submitted to ultrasonic inspection during planned maintenance shutdown. Continuous on-line AE monitoring of the integrity of critical welds is expected to contribute supporting continued and safe operation of the header until its replacement, platmed to take place in 1999. 

A comprehensive approach to the quality assurance in NDT would combine both approaches. It creates and maintains conditions for the people protection, safe operation of objects and products and preservation of the environment. 

The sodium fusion and extraction, if performed strictly in accordance with the above directions, should be safe operations. In crowded laboratories, however, additional safety may be obtained by employing the follow ing modification. Suspend the hard-glass test-tube by the rim through a hole in a piece of stout copper sheet (Fig. 69). Place 1 -2 pellets of sodium in the tube, and heat gently until the sodium melts. Then drop the organic compound, in small quantities at a time, down — =. the tube, allowing the reaction to subside after each addition before the next is made. (If the compound is liquid, allow two or three small drops to fall at intervals from a fine dropping-tube directly on to the molten sodium.) Then heat the complete mixture as before until no further reaction occurs. 

The steel shell that encloses the refractory is exposed to significant forces from the expansion of the refractory as well as the load from the refractory and the charge within the furnace. Similarly, the stmctures that support the furnace and the foundations must be designed to assure safe operation. A failure of any component can have serious consequences. 

Safe operation of ferromanganese furnaces requires careful control of raw material particle size, oxygen content of the ore blend, and charge stoichiometry (38). 

National Safety Council 444 North Michigan Avenue Chicago, Id. 60611 Industrial safety data sheets on materials and materials handling and safe operation of equipment and processes. 

Other RBMK reactors are still in operation in the former USSR. Some changes improving the prospects of safe operation have been made. 

The World Association of Nuclear Operators (WANO) has been formed, consisting of nuclear plant operators over the entire world who have pledged to assist each other in the achievement of safe operations (25). There are four centers from which this international program is adrninistered one in the United States in Atlanta, Georgia, operated by INPO one in Paris operated by Electricitir de Prance one in Moscow operated by the Ministry of Nuclear Power and one in Tokyo operated by the Central Research Institute for the Electric Power Industry (CRIEPI). Through this mechanism, teams of operators from the U.S., Western Europe, and Asia visit CIS plants to share safety experience and know-how, and similarly, plant personnel from Russian and Eastern European nuclear units visit European, Asian, and U.S. plants. 

The selection and appHcation of an expansion joint is not as simple as selecting a pipe fitting or a valve and requires a sound understanding of the joint s capabihties and limitations. Improper appHcation of any type of joint can result in serious or damaging effects. However, when properly selected and integrated into the piping system, satisfactory service and safe operation can be expected. Selection and appHcation of beUows expansion joints require special attention to design and installation. 

Personnel Selection and Training. The quaHty of operating personnel is of paramount importance to the safe operation of a chemical plant. Operators must be intelligent and emotionally stable. Excessive use of alcohol and dmgs affects reHabiHty and can thereby render workers more susceptible to certain types of toxic exposure. Thorough medical screening is essential to avoid damaging exposures to susceptible individuals, eg, people with respiratory ailments should not be employed in areas where corrosive atmospheres could occur. 

To maximize the performance of an FCCU, most units mn at one or more unit constraints. Frequently, one of these constraints is the regenerator temperature, which is set by metallurgical limits for safe operations. Process variables on both the reactor and the regenerator side are thus manipulated to keep the regenerator temperature as close as possible to this regenerator temperature limit. 

The analyses of the solutions in the electrolytic circuit and ceU operating data are given in Tables 5 and 6, respectively. The current efficiency of 45% shown in Table 6 includes low efficiencies that always prevail during the startup of a reconditioned cell. The 2.1—2.4 pH range used in the plant also results in somewhat lower current efficiency but provides a safe operating latitude. 

Flash points, lower and upper flammability limits, and autoignition temperatures are the three properties used to indicate safe operating limits of temperature when processing organic materials. Prediction methods are somewhat erratic, but, together with comparisons with reliable experimental values for families or similar compounds, they are valuable in setting a conservative value for each of the properties. The DIPPR compilation includes evaluated values for over 1000 common organics. Detailed examples of most of the methods discussed are available in Danner and Daubert."... 

The flash point is the lowest temperature at which a liquid gives off sufficient vapor to form an ignitable mixture with air near the surface of the liquid or within the vessel used. ASTM test methods include procedures using a closed cup (ASTM D56, ASTM DOS, and ASTM D3828), which is preferred, and an open cup (ASTM D92 and ASTM D1310). When several values are available, the lowest temperature is usually taken in order to assure safe operation of the process. 

Calvert found that reentrainment from the baffles was affected by the gas velocity, the liquid-to-gas ratio, and the orientation of the baffles. Horizontal gas flow past vertical baffles provided the best drainage and lowest reentrainment. Safe operating regions with vertical baffles are shown in Fig. 14-112. Horizontal baffles gave the poorest drainage... 

FIG. 14-112 Safe operating region to prevent reentrainment from vertical zigzag baffles with horizontal gas flow. (Calveii, Yung, and Leung, NTIS Puhl. PB-24S050, 1975.)... 

The key to safe operation is to provide an adequate means of charge dissipation from charged materi s to ground. This requires mobility of charges in or on the charged materialp/ii.s electrical continuity from the material to ground. 

Frequently a piece of equipment is used in different processes during its lifecycle. This could result in process conditions that exceed the safe operating limits of the equipment. Equipment inspection may provide a poor prediction of the equipment s useful life and reliability, due to the change of material handled or change in process chemistry over the life of equipment. Batch operations are also characterized by frequent start-up and shut-down of equipment. This can lead to accelerated equipment aging and may lead to equipment failure. This chapter presents issues and concerns related to the safe design, operation, and maintenance of various pieces of equipment in batch reaction systems, and provides potential solutions. 

Use of materials sensitive to shock, high temperature or high pressure. If the material is inadvertently exposed to an unsuitable condition, or if the process moves out of the safe operating limits, it could result in a loss of containment. 

Explosion testing should be performed to establish safe operating limits. Dust explosibility and ignitability are measurements of the potential for a combustible material, in dust form, to explode or ignite. Any combustible material has the potential to cause a dust explosion if dispersed in air as a dust and ignited. Further details on explosibility testing can be found in Palmer (1973), Bartknecht (1989) and Eckhoff (1997). 

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