Heat transfer and hydraulic stability in boiling-water reactors

Fundamental work on heat removal by bubble formation and by increased heat diffusivity as a result of increased turbulence in boundary layers is described. A math. model was constructed of the heat transfer loop that is in operation under pressures up to 40 atm. at input powers up to 600 kw., and inlet subcooling up to 40 Deg. The model is compared with the exptl. results obtained from the loop. The on-set of flow instability is studied, and the nature of the instabilities is characterized in the region up to burnout by means of analysis of power d. curves. The dynamic characteristics of the loop are studied by means of transfer function analysis. The validity of the underlying linearization is discussed and the resulting transfer functions are compared with those obtained from noise analysis. Systematic burnout studies of rod bundles are reported, including the analysis of flow instability preceding burnout