Feed water distribution system

After five years of operation in SG35, one feed water box and the corresponding distributing pipes were replaced with new ones during an NPP outage in order to allow an analysis of their overall condition and the corrosion products on their walls. For comparison, some parts of the original feed water distribution system from SG46 were cut out and analysed. 

The most corroded areas of the original feed water distributing system are the welds in the T-junction (see Figure 4.66). Due to dynamic effects of the feed water flow, with local dynamic overpressures of 20-30 kPa or local dynamic forces of up... 

The pH and dissolved solids content of a water supply are important factors, which relate to the corrosivity of the supply. Corrosivity is of concern in the lifetime of municipal water distribution systems, as well as for the feed water of power boilers and process cooling water. pHs in the neutral to slightly alkaline range are generally preferred for these applications. Most aquatic creatures... 

The basic 1977 design was improved after 1994 by installing a new feed water pipeline system. There was also a change in the type of steel used in these pipes. Instead of conventional carbon steel, austenite steel was used in the distribution boxes as well as the feed water pipes. 

The main advantage of this approach is that a visual inspection of the feed water pipe can be performed directly due to the placement of the whole water distribution system over the primary pipe bundle. Using this system, any potential defects are easier to observe. Another advantage arises from the seven boxes with ejectors that mix the feed water with boiler water, thus decreasing the thermal load. An additional advantage is that it is possible to check and exchange of the distribution boxes if they get damaged. 

In connection to the planned commissioning of Mochovce NPP 3 and 4 (announced officially on 3 October 2008), it is recommended that all feed water pipes and water distribution systems in the steam generators should be replaced immediately before starting operation with new ones constmcted from austenitic steels. The Bohimice design with feed water distribution boxes is highly recommended, and seems to be acceptable from a practical point of view. 

I heard of a case where the ultrapure water distribution system became contaminated with biological agents ( wee beasties ). The maintenance people knew how to solve the problem - they dumped pool chlorine in the water feed. It blew up the ion exchange columns. In another case, the top of the storage tank was left uncovered and seagulls left their waste in the storage tank. 

Water distribution must give uniform water flow over the tower packing. Many towers use a gravity feed system discharging the water through troughs and ceramic, metal... 

The 1-decanol/water distribution coefEcient for the nonionized form of erythromycin A was equal to 122 and was shown to be independent of the pH of the feed and/or the stripping phase. The apparent 1-decanol/water distribution coefEcient, that is, the ratio of the total concentrations of erythromycin in the aqueous phase and 1-decanol, varied strongly with the pH of the aqueous phase and decreased from 122 at pH values above 10.0 to 10 at the pH value of 7.0. When feed phase and the stripping phase compartments are both stirred independently and the stirring rates range from 250 to 1500 rpm, 60-50% of the initial erythromycin amount was recovered in the stripping phase after 10 h [154]. The low fluxes, and thus long treatment periods, were attributed by the authors to low surface to volume ratio of the SLM system used, that is, limited interface area available for the erythromycin transport into the SLM. For practical application, the interfacial area of the SLM available for the transport seems to be one of the main factors to be optimized. 

Since most protozoa feed on detritus and bacteria, their occurrence in drinking water is not unexpected [45]. Ciliate and amoeboid forms are commonly observed in uncovered finished water reservoirs [59] and amoebae have also been observed in uncontaminated distribution systems especially the geiiera Hartmanella, Naegleria, Echinamoeba and Acanthamoeba [45]. 

The second structure, the desalination barge, is a non-self-propelled structure housing systems and equipment providing for the supply of seawater to the desalination system, pretreatment of the feed supply, desalination, supply of desalinated water to the on-shore distribution system, and cleaning of the desalination units. 

Anticipated operational occurrences are off-normal events, usually plant transients, which can be coped with by the plant protection systems and normal plant systems but which could have the potential to damage the reactor if some additional malfunction should happen. Their typical frequency of occurrence may be more than 10 year Some of the anticipated occurrences (PIEs - postulated initiating events) are due to the increase of reactor heat removal (as might occur for an inadvertent opening of a steam relief valve, malfunctions in control systems, etc.). Some are due to the decrease of reactor heat removal (such as for feed-water pumps tripping, loss of condenser vacuum and control systems malfunctions). Some are due to a decrease in reactor coolant system flow rate, as in the case of a trip of one or more coolant pumps. Some are connected with reactivity and power distribution anomalies, such as for an inadvertent control rod withdrawal or unwanted boron dilution due to a malfunction of the volume control system for a PWR. Events entailing the increase or decrease of the reactor coolant inventory may also happen, due to malfunctions of the volume control system or small leaks. Finally, releases of radioactive substances from components may occur. 

Steam condensate is a valuable resource. It has considerable thermal value and some potential uses in the process. However, intensively treated boiler feed water must replace any condensate lost from the system. Accordingly, most plants have systems to capture most of the condensate and return it to the boilers. With steam distributed at several different pressures, it is also possible to allow condensate collected at one pressure to flash down to a lower pressure and in the process form more steam at the lower pressure. Steam is often available at the evaporators well above its condensing pressure, in which case it is worthwhile to install a desuperheater. Condensate is a good source of the coolant. 

Strict control of purity relies on the avoidance of corrosion in the steam-distribution system and on chemical treatment of the feed water or steam condensate [15]. Treatment chemicals may include ... 

Fountain faun-t n [ME, fr. MF fontaine, fr. LL fontana, fr. L, feminine of fontanus of a spring, fr. font-, fans] (14c) n. Part of a printing press, which contains the ink to be fed to the distributing system. In hthography, it is also the part, which feeds the water or fountain solution to the dampening rollers. 

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