The Relative Stability of Boiling and Pressurized Light Water Moderated Reactors

This paper compares the stability of a given heterogeneous core when operated with a pressurized or subcooled water cooling system in which the power is removed by boiling. In order to provide a basis for comparison the following assumptions are made: 1) reactor power is the same in both cases, 2) the core geometry is the same in both cases, 3) in the case of subcooled operation, coolant flow rate and core inlet temperature are held constant, and 4) in the case of boiling operation reactor pressure is constant. Assumptions 3) and 4) imply that the load equals power generated at all times. The core geometry and the values of the various system parameters are taken from published literature wherever possible. It is shown that the results of this analysis are readily predictable from physical reasoning.