Reactor water conditions

The data suggest that iodine will be released, predominantly, as cesium iodide under most postulated light water reactor accident conditions. However, formation of more volatile iodine species (e.g., elemental iodine and organic iodines) is not impossible under certain accident conditions. 

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)... 

Where condenser in-leakage develops in nuclear reactor boilers, calcium hideout may occur in the reactor water, implying that some leakage of Ca and Mg may have occurred from the condensate polishers. There also may be some sodium or chloride leakage from the polishers (under good conditions, the polisher effluent usually contains below 0.1 ppb Na). 

The next two steps after the development of a mathematical process model and before its implementation to "real life" applications, are to handle the numerical solution of the model s ode s and to estimate some unknown parameters. The computer program which handles the numerical solution of the present model has been written in a very general way. After inputing concentrations, flowrate data and reaction operating conditions, the user has the options to select from a variety of different modes of reactor operation (batch, semi-batch, single continuous, continuous train, CSTR-tube) or reactor startup conditions (seeded, unseeded, full or half-full of water or emulsion recipe and empty). Then, IMSL subroutine DCEAR handles the numerical integration of the ode s. Parameter estimation of the only two unknown parameters e and Dw has been described and is further discussed in (32). 

Later, Yoshida et al. reported the dehydration of fructose to HMF in a batch-type reactor under subcritical water (sub-CW) and with different zirconium phosphate solid acid catalysts at 240°C (Scheme 7) [77]. Over amorphous zirconium phosphate, 80% of fructose was converted after 120 s affording HMF with a selectivity of 61%. Interestingly, no side product stemming from the rehydration of HMF was detected in this case. However, soluble polymers and furaldehyde were detected as side products. Remarkably, zirconium phosphate solid catalysts were stable under subcritical water conditions and were reused without any loss of their activity. 

In its present commercial operations Sasol uses two types of reactors. In the fixed bed "low" temperature Arge reactors the gas enters at the top (see Figure 2). The catalyst is packed into the narrow tubes. The FT reaction heat is absorbed by the water surrounding the tubes and steam is generated. The desired reactor temperature is maintained by controlling the steam pressure above the water jacket. The catalyst formulation and the reactor process conditions are set for the maximum production of high quality paraffinic waxes. Only the Sasol One plant utilizes these reactors. 

Spent fuels vary in microstructure, and phase and elemental distribution depending on the in-core reactor operating conditions and reactor history. The chemical stability of spent U oxide fuel is described by local pH and Eh conditions, redox being the most important parameter. However, the redox system will also evolve with time as various radionuclides decay and the proportion of oxidants and reductants generated at the fuel/water interface changes with the altering a-, (J-, y-radiation field and with the generation of other corrosion products that can act as... 

Initial studies of phenol SCWO Involved in extensive SCWO study Investigated the unique features of supercritical water in terms of density, dielectric constant, viscosity, diffusivity, electric conductance, and solvating ability Treatment of hazardous organic compounds Application of SCWO to the decomposition of sludges Found that sludge readily decomposes at near-critical water conditions with 02 or H202 as an oxidant in a batch or continuous flow reactor Treatment of sludges... 

Carbon monoxide is compressed and sparged into the reactor riser. The reactor has no mechanical moving parts, and is free from leakage/ maintenance problems. The ACETICA Catalyst is an immobilized Rh-complex catalyst on solid support, which offers higher activity and operates under less water conditions in the system due to heterogeneous system, and therefore, the system has much less corrosivity. 

A liquid stream from the charge tank is heated from 24°C to 149°C and fed to the reactor, along with a stream of ammonia vapor at 108°C and 4.5 bar. The total ammonia fed to the reactor is 5% in excess of the amount needed to react completely with the nitric acid In the feed. At the reactor operating conditions, the ammonium nitrate is formed as liquid droplets and most of the water in the acid is vaporized. The reaction goes to completion. 

Figure 14 Flow visualization experiments showing effect of varying gap between OCFS and wall. Ink pulse injected into a water stream flowing (right to left) through an (XTFS, at two radial locations, in the structure and in the gap (bottom of each picture). From top to bottom successively increasing flow rates (corresponding to Reynolds numbers representative of reactor operating conditions) in a structure with a smal/ (desirable) wall gap. (From Ref. 10.)...

The primary coolant circuit of a water-cooled reactor (including BWRs and PWRs) has several loops, including the main coolant loop, a core heat removal system, and a reactor water cleanup system. However, it is convenient, for computational purposes, to differentiate between the main loop, which has a high flow fraction, and the secondary loops, for which the flow fractions are small. The species concentrations and electrochemical potential (ECP) are solved for in the main loop and the values at the entrance to the secondary loop are used as the initial conditions for solving the system of equations for the secondary loops of interest. Mass balance is applied at each point where more than one section comes together. 

The primary coolant circuit of a PWR is shown in schematic form in Fig. 36. In this particular circuit, there are four loops between the reactor and the steam generators. The pressurizer is also shown, which maintains the pressure in the primary loop at a sufficiently high value (typically 150 bar) such that sustained boiling does not occur and maintains the desired concentration of hydrogen in the coolant. The reactor heat removal system (RHRS) and the reactor water cleanup system are not shown. The general operating conditions in a PWR primary loop are summarized in Table 2. 

Use Water conditioning (softening and complete deionization), recovery and concentration of metals, antibiotics, vitamins, organic bases, catalysis, de-colorization of sugar, manufacture of chemicals, neutralization of acid mine-water drainage, analytical chemistry, water treatment in nuclear reactors, pharmaceuticals. 

In future generations of nuclear reactors - especially supercritical water reactors (SCWR), 4th generation nuclear reactors and the ITER project (International Thermonuclear Experimental Reactor) - water should still be considered as a suitable coolant fluid, but it will be submitted to more extreme conditions of temperature and LET (high flux of neutrons). All contemporary studies show that it will be beyond reach to extrapolate the existing simulations to these new conditions without experimental determinations of essential parameters such as radiolytic yields and rate constants. 

In addition to performing reactions at room temperature, the excellent thermal control obtained within flow reactors enables conditions that would conventionally be termed extreme to be used with ease. An excellent example of this was demonstrated by Kawanami et al. [24], whereby a superheated Hastelloy micro mixer (0.5 mm i.d.) and tubular flow reactor [1.7 mm i.d. x 10 m (length)] was used to create rapid collision mixing between a substrate and water, the resulting particle dispersion was then rapidly heated, to induce a reaction, and cooled to afford a binary... 

Gas-phase reactions are usually performed with a series of fixed bed adiabatic reactors with re-heating between each catalytic bed. Liquid-phase reactions are usually performed in a slurry reactor with a circulating inert gas. The new trends in dehydrogenation reactors and conditions are membrane reactors [12], wall reactors [13], reactions performed in supercritical water [14], and oxidative dehydrogenation [11],... 

Further analysis and calculations have shown that these natural Oklo reactors (similar conditions occurred at several places) lasted for 10 y. Probably, criticality occurred periodically as the heat from fission boiled away the water so that the chain reaction ceased after a while. After water returned (as the temperature decreased) the chain reaction would... 

If the feed mole ratio of water to methane is X, and if equilibrium is achieved at reactor effluent conditions of 1073 K and 200 psia, determine the composition of the effluent gas for values of X from 1 to 10. Prepare plots of the extents of reactions (I) and (II), as well as plots of the fractions of the original CH4 that are converted to CO and CO2 versus X. 

A purchasable cross-flow heat exchanger for application in laboratory-, pilot- and production-scale plants was developed by FZK. By incorporation of a catalyst on the quadratic plates inside the heat exchanger, it can also be used as a catalytic wall reactor. Operating conditions up to 850 °C (stainless steel) and pressures of more than 100 bar are possible, and the specific inner surface area is up to 30 000 m m. The reactors can be obtained in many materials and three different sizes with a maximum flow of 6500kgh (water). Therefore, the reactors can be adjusted for various processes, and all types of catalyst deposition techniques are possible [111]. This reactor has already been applied to the catalytic oxidation of H2 by Janicke et al. [112], for example. 

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