Reactor volumetric heat generation

The average volumetric heat generation rate q" (W/m ) in the reactor core is given as the product of total reaction rate R (1/s) and the energy per reaction Gf (J). The reaction rate R is calculated as... 

Qian, L., Qiu, S., Zhang, D., Su, G.H., Tian, W., 2010. Numerical research on natural convection in molten salt reactor with non-uniformly distributed volumetric heat generation. Nuclear Engineering and Design 4. 

In a core melt accident of a LWR, a feasible option for arresting the progress of the accident, before the reactor pressure vessel (rpv) melt-through, is to provide cooling for the rpv bottom externally by submerging the lower part of the vessel in water. The effectiveness of the external cooling in such a case is determined by the volumetric power generation and the heat flux distribution from the corium on the rpv lower head on one hand, and by the capability to efficiently vent the steam produced from the reactor cavity to the upper compartments of the containment on the other hand. 

In these balance equations all terms should be described at the same level of accuracy. It certainly does not pay to have the finest description of one term in the balance equations if the others can only be very crudely described. Current demands for increased selectivity and volumetric productivity require more precise reactor models, and also force reactor operation to churn turbulent flow which to a great extent is uncharted territory. An improvement in accuracy and a more detailed description of the molecular scale events describing the rate of generation terms in the heat- and mass balance equations has... 

The sensible heat of the purge gas vented to atmosphere from the fluidized bed process can be as low as 30% of that in the fixed bed process because of lower gas volumetric flow. Therefore for a given reactor capacity more of the reaction heat is recovered in generating steam. 

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