Steam binding

The acceptance criteria for the resolution of GSI 093 are that the design of the EFW system shall be such that the potential for steam binding of the EFW pumps is minimized and that the EFW system shall meet the intent of GL 88-03. 

The main defense against steam binding of the EFW Pumps results from the system design for normal plant operation. 

This alarm warns the operator that leakage through the steam generator isolation valve and check valve is occurring. Therefore, these sensors provide indication to the operator of the potential of steam binding of the EFW pumps. 

Generic Letter 88-03, "Steam Binding of Auxiliary Feedwater Pumps , U.S. Nuclear Regulatory Commission. 

Fig. 12.6. Variation of main parameters following large break in coolant circuit of PWR. Curves 1 and 2 show the core mass flow rates for the inlet and outlet breaks, respectively. For an inlet break, the rapid reduction in flow causes a steep rise in cladding temperature (curve 3) the rise is less rapid for the outlet break (curve 4). The pressure drops continuously for either type of break (curve 5). For an outlet break, the water level starts to rise again (curve 7) shortly after initiation of the ECCS, but for the inlet break (curve 6) the water level rises more slowly owing to steam binding and entrainment of the injected coolant [from APS Study Group Report, Rev. Mod. Phys. 47, Suppl. 1 (1975)].

Vapor binding, or air lock, is another common cause of household radiator malfunction. Often, the vapor accumulating in the radiator is CO,2, rather than air. The C02 originates from the thermal decomposition of carbonates in the boiler. Regardless, air and C02 form a noncondensable vapor in the radiator. These noncondensables mix with the steam in the radiator. The noncondensables then reduce the concentration of the steam, by dilution. The diluted steam has a lower partial pressure than pure steam. The lower the partial pressure of the steam, the more difficult it is to condense. As the rate of condensation of the steam drops, so does the heat radiated by the radiator. 

Furfural is obtained commercially by mealing pentosan-rich ugricullural residues (corncobs, oat hulls, cottonseed hulls, hagasse. rice hulls) with a dilute acid and removing the furfural by steam distillation. Major industrial uses of furfuraldehyde include (1) the production of t urnns and tetrahydrofurans where the compound is an intermediate (2) Ihc solvent refining of petroleum and rosin products (3) the solvent binding of bonded phenolic products and (4) the extractive distillation of butadiene from other C4 hydrocarbons. 

Test Samples. Main properties of the residual oils used in the present test are represented in Table II. It should be noted in this table that No. 1 is propane deasphalted asphalt Nos. 2 to 7 are petroleum pitches derived from residual oil heat treated under various conditions No. 8 is KRP pitch made by Kureha Chemical Industry from crude oil heat treated with hot steam at temperatures over 1,000°C and Nos. 9 and 10 are both residual oils from coal, No. 9 being solvent refined coal made by NKK and No, 10 being heat treated coal tar pitch. These Nos. 1 to 10 are typical examples of binding material for coke-making in Japan. 

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