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Atomic Weight/Hydrogen Isotopes
Injection of Air - h1015v2_44

Chemistry Volume 2 of 2
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Reactor Water Chemistry DOE-HDBK-1015/2-93 CHEMISTRY PARAMETERS Rev. 0 CH-03 Page 25 Solubility Hydrogen gas (including tritium gas) dissolves to some extent in most materials.  Tritium and deuterium behave like protium, except for small isotopic effects.  Hydrogen atoms or diatomic hydrogen molecules and some larger hydrogen-bearing molecules dissolve interstitially; that is, they diffuse into a structure and locate between atoms or molecular frameworks.  As it dissolves, the hydrogen slightly disrupts the structural networks of the material and causes expansion.  The extent of the disruption, along with the extent of chemical attractive/repulsive forces between the hydrogen and the material, determines the ultimate equilibrium state. Solubility in Polymers, Glasses, and Ceramics Hydrogen gas dissolves as the molecular hydrogen species in many materials.  For these systems,  solubility  is  generally  endothermic  and  is  directly  proportional  to  gaseous overpressure.  The materials in which hydrogen dissolves as the molecular species include organic  polymers  and  glasses  at  less  than  150   C.    Organic  polymers  generally  have atomic-scale voids in the twisted polymer chain, and the hydrogen molecules seek these sites.  Hydrogen dissolution in glasses is assumed to be similar. Abnormal Chemistry Conditions As indicated earlier in this module, there are times when actions taken regarding one specific chemistry parameter may affect more than that parameter (such as feed and bleed operations). This may also be the case during many abnormal conditions that the reactor coolant system may be subjected to. In  this section, we will consider the conditions resulting from injection of air, fuel element failure, and overheating of resin and discuss the probable changes to other chemistry parameters that may occur. Injection of Air Injection  of small and large amounts of air into the reactor coolant system was previously analyzed.  When sufficient oxygen is added to deplete the hydrogen inventory, acidic pH results in those facilities where high (basic) pH is maintained.  This reduction in pH is accompanied by secondary effects to the coolant.  The reduced pH causes a change in solubility of the corrosion film on facility materials and results in part of this film being released for transport throughout the coolant system.  This release, or crud burst, is detected by an increase in radiation levels of the coolant, increased conductivity, and lowering of the ion exchanger efficiency.  Radiation levels increase because corrosion products that had been attached to core surfaces and were highly activated by the neutron flux are transported to other parts of the system.







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