Calculation of Departure From Nucleate Boiling Conditions for the Spert Iii Reactor in the High Pressure Region

Calculations are made to determine the safe steadystate power operating limits of the Spert III reactor from the viewpoint of fuel plate burnout. A computer program is developed for the IBM 704 to aid in these calculations. The Bettis design departure from nucleate boiling (DNB) equation is used in conjunction with the LeTourneau and Grimble method of hot channel'' analysis in the development of the calculations. For cases where DNB occurs in the bulk boiling region, a modified Martinelli-Nelson twophase flow correlation and some experimental singlephase pressure drop data are employed. DNB for a typical operating condition of 550 deg F inlet temperature and 2500 psig is computed to check the code. The results of the sample calculation show that at a steady- state power level of 60 Mw (maximum design power) the minimum flow rate required to prevent DNB is approximately 8000 gpm. (auth