Normal operation conditions

Levels of radiation, temperature or pressure in normal operation conditions will affect the physical properties of a material. Radiation affects components in and outside the reactor core. Other components may be affected by radiation from radioactive materials circulating with the coolant. While the effects of temperature and pressure are more noticeable in power reactors, they are also present in research reactors in materials such as gaskets. Cycling temperature or pressure variations may accelerate deterioration. Table I provides summary information on specific ageing mechanisms. Additional information on these topics is given in Appendix IV which lists 12 case studies. Further information on material ageing mechanisms related to nuclear power plants but sometimes applicable to materials used in research reactors can be found in Ref. [2]. 

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Under normal operating conditions, waste is produced in reactors in six ways ... 

Regulations require that the incinerator furnace be at normal operating conditions, including furnace temperature, before hazardous wastes are injected. This requires auxiUary fuel burners for furnace preheating. In addition, the burners provide heat when the wastes burned are of low heating value. Auxihary burners are sized for conditions where Hquid wastes are injected without the addition of high heating value wastes. 

Sihcone fluids have good dielectric properties, loss factor, specific resistance, and dielectric strength at normal operating conditions, and the properties vary only slightly with temperature (59,328,350). The properties in combination with relatively low flammabiUty have led to the use of siUcones in transformers and other large electrical appHcations (351). The dielectric constant of a 1000-cSt oil is 2.8 at 30°C and 2.6 at 100°C. The loss factor is low,... 

Thermal expan sion. Equipment and pipehues which are liquid-full under normal operating conditions are subject to hydrauhc expansion if the temperature increases. Common sources of heat that can result in high pressures due to thermal expansion include solar radiation, steam or other heated tracing, heating coils, and heat transfer from other pieces of equipment. 

Under normal operating conditions, the concentration of the trioxide is unlikely to exceed 10 ppmv, but this is sufficient to elevate the acid dew point to around 422 K (300°F). This places a limit on the lowest acceptable back-end temperature if acid condensation and resulting corrosion problems are to be avoided. 

In Table 11.6 the values of colurrm 2 relate to normal operating conditions. Abnormal conditions may prevail when the machine is exposed to overhead lines, the... 

The sizes of cables considered above refer to normal operating conditions and a distance of around 10/15 metres between the starter and the... 

Step 1. Selection of normal operating conditions for the regenerator system. This sets normal air blower flow and head, and expander flow and head. If the proposed installation is being designed for an existing FCC unit, only a... 

Turboexpander sensitivity to process gas inlet pressure. As previously mentioned, variable speed turboexpanders are more sensitive to changes in normal operating conditions. Tlie pattern of TTE degradation, however, is the same as for constant speed turboexpanders (Figure 7-13a). In other words, TTE is more sensitive to pressure drop than to pressure rise. For instance, a 20% drop in gas inlet pressure will reduce TTE to 90% of the design value, whereas a 20% increase in gas inlet pressure reduces TTE to 99% of the design value. 

Under normal operating conditions the first wall must handle high plasma surface heat fluxes (Table 1), as well as volumetric heat loadings due to the penetrating neutron and electromagnetic radiation. The volumetric heat loading is dependent... 

A single-column system for liquid-phase carhon adsorption is used in situations where the following conditions prevail laboratory testing has indieated that the breakthrough curve will be steep the extended lifetime of the earbon at normal operating conditions results in minor replacement or regeneration eosts the eapital... 

When determining pressure rehef requirements, one should calculate capacities of control valves for the relieving conditions of temperature and pressure, since these are in many cases significantly different from capacities at normal operating conditions. Downstream equipment must be analyzed imder relieving conditions. 

The quantity of material to be relieved should be determined at conditions corresponding to the PR valve set pressure plus overpressure, not at normal operating conditions. Frequently, there is an appreciable reduction in required PR valve capacity when this difference in conditions is considerable. The effect of friction pressure drop in the connecting line between the source of overpressure and the system being protected should also be considered in determining the capacity requirement. If the valve passes a liquid which flashes or the heat content causes vaporization of liquid, this should be considered in determining PR valve size. 

A typical pilot-operated PR valve is illustrated in Figure 5. Under normal operating conditions, the vessel pressure acts on the main valve seat at the bottom of the free-floating differential area piston, and by means of the pilot supply line is also applied to the top of the piston and under the pilot valve disc. Since the top area of the piston is larger than the nozzle area at the lower end of the piston, there is a large net load holding the piston down on the nozzle. Under static... 

Inherently safe A system is inherently safe if it remains in a non-hazardous situation after the occurrence of non-acceptable deviations from normal operating conditions. 

Use materials that are applicable over the full range of operating conditions such as normal, startup, routine shutdown, emergency shutdown, and draining the system. For example, carbon steel may be acceptable for normal operating conditions but may be subject to brittle fracture at low temperatures under abnormal conditions (as in the case of a liquefied gas). Cold water, of less than 60°F, during hydrotest may cause brittle fracture of carbon steel. 

Under normal operating conditions the worker will be situated outside the enclosure. The operator will enter the hood only with his or her hands/arms. During the setting up of equipment it may be necessary to enter the enclosure, but entry should be kept to a minimum and, whenever possible, before the emission of contaminant has commenced. 

A nonincendive device is one which will not release sufficient energy under normal operating conditions to ignite a specific substance. Under abnormal conditions, such as a malfunction of the device, it may release enough energy to cause ignition. Because of this, such devices are suitable for use only in Division 2 and unclassified areas. 

The impact of the system design on human performance should be examined during this phase. The designer should consider whether or not the operator will be able to keep the system operating correctly under normal conditions and is he or she able to effectively handle unusual conditions, returning them to normal operating conditions. Observation of persormel and discussions with them are effective ways that should be employed in this phase. Where necessary, appropriate modifications should be made to the system to ensure proper performance. 

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