Primary water

The primary water specifications for a PWR are given in Table 1 (4). Rigid controls are appHed to the primary water makeup to minimise contaminant ingress into the system. In addition, a bypass stream of reactor coolant is processed continuously through a purification system to maintain primary coolant chemistry specifications. This system provides for removal of impurities plus fission and activated products from the primary coolant by a combination of filtration (qv) and ion exchange (qv). The bypass stream also is used both to reduce the primary coolant boron as fuel consumption progresses, and to control the Li concentrations. 

The BWR water chemistry parameters are given in Table 4 (19). Originally, no additives were made to feedwater—condensate or the primary water. The radiolytic decomposition of the fluid produced varying concentrations of O2 in the reactor vessel, ranging from about 200 ppb O2 in the reactor recirculation water to about 20 ppm O2 in the steam. Stoichiometric amounts of hydrogen were also produced, ie, 2 mL for each mL of O2. Feedwater O2 was about 30 ppb, hence the radiolytic decomposition of the water was a primary factor in determining the behavior of materials in the primary system and feedwater systems. 

PWR Primary Water Chemistry Guidehnes Revision 2," Report NP-7077, Electdc Power Research Institute, Palo Alto, Calif., Nov. 1990. 

Wa.ter Qua.litySta.nda.rds, The first step in water quahty standards is stream use classification. The individual states must decide what the uses of their water will be. The four categories, as defined by the EPA, are Class A, primary water contact recreation Class B, propagation of desirable aquatic life Class C, pubHc water suppHes prior to treatment and Class D, agricultural and industrial uses. States may vary the definition of these classes to meet their own needs. The second step is to develop water-quaHty criteria. This is the specific concentration of a pollutant that is allowable for the designated use. 

Parking areas Primary water treatment—filtration, coagulation, aeration... 

The vessel is a 15 ft high cylinder with a diameter of 16.25 ft constructed of half-in thick, type 304 stainless steel plate. Six outlet nozzles are uniformly spaced around the circumterence at the bottom, and six tapered inlet nozzles are uniformly spaced around the circumference of the water plenum at the top of the vessel. The primary water system PWS contains 40,000 gal of DjO 24,000 gal in the re tank and 16,000 gal in the piping system. Each of the six primary loi ted... 

Chul Kim, U. R. and van Rooyen, D., Strain rate and temperature effects on the stress corrosion cracking of Inconel 600 steam generator tubing in the (PWR) primary water conditions , Proc. 2nd Int. Conf. on Environmental Degradation of Materials in Nuclear Power Systems-VIalet Reactors, Monterey, USA, 9-12 Sept. 1985, American Nuclear Society, pp. 448-55 (1986)... 

Adjunct online cleaning programs. Here, the primary water treatment program continues to be provided and a supplementary product or formulation is added temporarily, specifically to remove the foulant. 

Stand-alone online cleaning programs. The primary water treatment program is discontinued for a period until the foulant has been removed, after which the original program or a modification is reinstituted. 

In this section we link our discussion in two previous sections dealing with structure of water and with ion-water interaction. In the discussion on ion-water interaction it was shown that ions in water arrange their immediate neighboring water dipoles into a local structure of the primary water of hydration. Between this local structure and the bulk water is the nonstructured secondary water of hydration. Thus, the presence of ions in water will change the number of water molecules in both the structured and unstructured regions. Any decrease in the number of water molecules in a cluster will result in a corresponding decrease in the value of g and thus a decrease in the dielectric constant of water [Eq. (2.4)]. 

The process at Three Mile Island involved nuclear fission and subsequent reactor cooling using circulating water. The primary water was kept under pressure to prevent boiling. Heat was transferred to a secondary water system that supplied power to a steam generator. Upon completion of this step, steam condensate was recovered and recycled. All radioactive materials, including primary water, were enclosed in a lined concrete containment building to prevent their escape to the atmosphere. 

The second row is largely reserved for solvated ions. The locus of centers of these solvated ions is called, for historical reasons, the outer Helmholtz plane, hereafter referred to as OHP (Fig. 6.61). On top of the first-row water (the primary water layer) and in between the solvated ions are other water molecules, a sort of secondaty hydration sheath, feebly bound to the electrode. 

A vety important question now arises. Does this arrangement of hydrated ions in contact with a hydrated electrode always correspond to the configuration of lowest free energy Are some ions capable of divesting themselves (at least partly) of their primary waters, making their way through the hydration sheet of the electrode, and coming into contact with it ... 

In Chapter 2 it was said that the number of hydration molecules as well as the hydration energy depends mainly on the charge and size of the ion. Thus, small cations have a large number of hydration molecules attached strongly to the ion. They cannot easily get rid of their hydration sheet. They will not contact adsorb on the electrode. On the contrary, large anions and large cations have only a few primary water molecules or none loosely attached to the ion. For them, the ion-solvent interactions are less important than other interactions. They will tend to contact adsorb on the electrode (Fig 6.91). 

To protect the condensote coalescer from plugging by any fine solids carried over from the primary water/condensote separator a Condensate Filter was installed upstream of the coalescer to remove all particles larger thon 5 micron. 

Bromide Primary alkyl- H H Sn2 transition state Primary Water... 

The Ion-Dipole Model. In this model ion-dipole forces are the principal forces in the ion-water interaction. The result of these forces is orientation of water molecules in the immediate vicinity of an ion (Fig. 2.11). One end of the water dipole is attached electrostatically to the oppositely charged ion. The result of this orienting force is that a certain number of water molecules in the immediate vicinity of the ion are preferentially oriented, forming a primary hydration shell of oriented water molecules. These water molecules do not move independently in the solution. Rather, the ion and its primary water sheath is a single entity that... 

In this discussion we link two previous sections (1) structure of water and (2) ion-water interaction. In the discussion on ion-water interaction, it was shown that ions in water arrange their immediate neighboring water dipoles into a local structure of the primary water of hydration. Between this local structure and the bulk... 

The fresh waters supplied to the Black Sea with the riverine runoff and precipitation are distributed by currents and turbulence over the upper layer of the sea with a thickness of 5-10 m in the spring and summer and up to 40-60 m at the end of the winter. Usually, the water salinity in this layer is within the range 17.5-18.5 psu. The saline (35-36 psu) waters of the Sea of Marmara flow in the southwestern part of the Black Sea through the Bosporus Strait at a level of 60 m and sink to the deeper layers. Thus, in the multiannual mean (climatic) regime, the depth of 60 m represents the boundary of the direct influence of the surface fresh waters and the saline waters of the Sea of Marmara. They may be referred to as primary water masses, supplied to the Black Sea from outside, which have no direct contact in the Black Sea. 

In the most general form, the isolated characters of the primary water masses from one another are expressed in the thermohaline (T,S) diagram shown in Fig. 2a, where each point represents a spatially fixed water volume (within a spherical trapezium with sides 12 min over the latitude and 16 min... 

The T,S structure of the Black Sea waters presented in Fig. 3 is caused by the weak turbulent diffusion below the UML, which is characterized by a diffusivity of about 10 5 m2 s 1 [6,7,11-13], which is one to two orders of magnitude lower than the values usual in the open ocean. The reason for the weak vertical turbulent exchange in the Black Sea is the great differences in the densities of the primary water masses (the freshwater mass and that of the Sea of Marmara). 

A novel method for determining the location of the primary water adsorbing sites has been developed by Bailey et al., (1995). This approach involves the pre-adsorption of naphthalene, which was chosen because of its planar molecular shape and immiscibility with water. With some activated carbons it was found that the growth of the H-bonded water clusters was inhibited by the presence of naphthalene, while in other cases there was very little effect. It was thought that sites in larger micro-pores were prone to obstruction by the pre-adsorbed naphthalene. It is too early to judge the success of this interesting approach, which may turn out to be a useful alternative to pre-adsorption by n-nonane. 

Conversion of primary water radicals into secondary radicals... 

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