Coolant additions

Strategies aimed at preventing or mitigating core damage all focus on getting coolant to the fuel to reduce the fuel temperature. To die extent that these measiues do cool the fuel or, at least slow the temperature rise, they also mitigate radionuclide release that is so very dependent on temperature. 

Flooded release pathways created by coolant addition were responsible for the relatively modest radionuclide releases to the containment during the Three Mile Island accident. Gas flows through flooded pathways are broken into bubbles. Radioactive vapours and aerosols are removed from the bubbles by processes that are quite like those that occur in steam suppression pools. These removal processes are also discussed in Chapter V. 

On the other hand, coolant additions insufficient to quench the degrading reactor fuel may enhance the release of radioactivity from die reactor coolant system. Enhanced releases can come about because the enhanced availability of steam for reaction widi zirconiiun clad leads to higher fuel temperatures. Higher steam concentrations can make some radionuclides more volatile. Or, enhanced releases may be caused simply because higher steam production leads to more efficient mass transport through the reactor coolant system. 

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Contamination of oil by water or coolant can cause major problems in a lubricating system. Many of the additives now used in formulating lubricants contain the same elements that are used in coolant additives. Therefore, the laboratory must have an accurate analysis of new oil for comparison. 

Select the engine coolant or antirust with care to ensure adequate corrosion protection. Use only those products conforming to recognized standards such as ASTM D 3306 for engine coolant. Additionally, if your vehicle engine contains major cast aluminum components, be certain the engine coolant meets the heat rejection corrosion limits in ASTM specification D 3306 as determined by ASTM Test Method for Corrosion of Cast Aluminum Alloys in Engine Coolants Under Heat-Transfer Conditions (D 4340). 

Withstand the chemical environment (hydrogen, air, water, coolant additives). 

This report discusses the positive and negative features of coolant addition as a means to arrest or mitigate a core degradation accident. It focuses on the accident progression aspects of accident mitigation and does not address some of the more important consequences of coolant additions on fission product release and behaviour. There does not seem to be in the literature a corresponding analysis of the source term issues associated with coolant additions. 

The requirements for radiator tanks are good heat stability, vibration resistance, and resistance to coolant additives [18],... 

K. Sato, M. Yasukawa, A. Sagasaki, T. Wada, and Y. Kato, Fuel cell system including coolant additive and ion exchange resin and fuel-cell vehicle, US Patent 8951689, assigned to Suzuki Motor Corporation (JP) Showa Water Industries Co., Ltd. (JP), February 10,2015. 

Propellants, explosives, pyrotechnics. Initiators, ceramic additives, conductive coatings, coolant additives, high thermal conductivity materials, sintering additives... 

Space Nuclear Power Plant (SNPP) electric power output could be controlled on reactor outlet temperature and Brayton speed. Mass inventory control (system pressure) was not pursued based on increased complexity and the additional risks to spaceship performance introduced by such a system (e.g., inadvertent coolant addition, additional leak paths). 

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