Boiling water reactors systems concentrations

AVT Barg BD BDHR BF BOF BOOM BOP BS W BSI BTA Btu/lb BW BWR BX CA CANDUR CDI CFH CFR CHA CHF CHZ Cl CIP CMC CMC CMC COC All-Volatile treatment bar (pressure), gravity blowdown blowdown and heat recovery system blast furnace basic oxygen furnace boiler build, own, operate, maintain balance of plant basic sediment and water British Standards Institution benzotriazole British thermal unit(s) per pound boiler water boiling water reactor base-exchange water softener cellulose acetate Canadian deuterium reactor continuous deionization critical heat flux Code of Federal Regulations cyclohexylamine critical heat-flux carbohydrazide cast iron boiler clean-in-place carboxymethylcellulose (sodium) carboxy-methylcellulose critical miscelle concentration cycle of concentration... 

Asakura, Y, Uchida, S., Ohsumi, K., Shindo, T., Aizawa, M., Usui, N., Amano, O., Yoshi-kawa, S., Otoha, K. Current operating experience with water chemistry in crud concentration suppressed boiling water reactors. Proc. 5. BNES Conf. Water Chemistry of Nuclear Reactor Systems. Bournemouth, UK, 1989, Vol. 1, p. 115-122 Asay, D. Radiation-field buildup at the Monticello BWR with hydrogen water chemistry. Report EPRI NP-7520 (1991)... 

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. 

In most industrially relevant reacting systems, one main reaction typically makes the desired products and several side reactions make byproducts. The specific rate of production or consumption of a particular component in such a reaction set depends upon the stoichiometry and the rates. For example, assume that the main reaction for making vinyl acetate, Eq. (4.4.1, proceeds with a rate r< (mol/L s) and that the side reaction, Eq. (4.8), proceeds with rate r2 (mol/L s). Then the net consumption of ethylene is (-l)r1 - (-1 )r2 (mol/L s). Similarly, the net consumption of oxygen is (-0.5)fi + (— 3)r2, and the net production of water is (l)r-, + (2)ra. For a given chemistry (stoichiometry), our ability to control the production or consumption of any one component in the reactor is thus limited to how well we can influence the various rates. This boils down to manipulating the reactor temperature and/ or the concentrations of the dominant components. Occasionally, the reaction volume for liquid-phase reactions or the pressure for gas-phase reactions can also be manipulated for overall production control. These are the fundamentals of reactor control. 

Heavy fuel deposits were expected in boiling systems, and therefore the initial studies of deposition and activity transport for power reactors concentrated on the CANDU-BLW concept until the fields at Douglas Point became a concern. The deposit thickness was proportional to iron concentration in the coolant and to the square of the heat flux (69) deposition was reversible and quickly reached a steady value set by the local conditions. The corrosion products initially deposit by hydrodynamic and electrostatic effects then boiling accelerates deposition by drawing water and its contained iron into the deposit to replace the steam that leaves. Local alkalinity gradients within the deposit determine whether iron crystallizes to cement the deposit or dissolves to weaken it, and erosion processes then define the equilibrium thickness (70), This model works well in explaining deposition under boiling conditions. 

With pervaporation membranes the water can be removed during the condensation reaction. In this case, a tubular microporous ceramic membrane supplied by ECN [124] was used. The separating layer of this membrane consists of a less than 0.5 mm film of microporous amorphous silica on the outside of a multilayer alumina support. The average pore size of this layer is 0.3-0.4 nm. After addition of the reactants, the reactor is heated to the desired temperature, the recyde of the mixture over the outside of the membrane tubes is started and a vacuum is apphed at the permeate side. In some cases a sweep gas can also be used. The pressure inside the reactor is a function of the partial vapor pressures and the reaction mixture is non-boiling. Although it can be anticipated that concentration polarization will play an important role in these systems, computational fluid dynamics calculations have shown that the membrane surface is effectively refreshed as a result of buoyancy effects [125]. 

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