Transient Analysis of the Tmi-2 Pressurizer.

A computer model has been developed to simulate the dynamic behavior of a pressurized water reactor (PWR) pressurizer system subjected to severe transients. Although the focus of this investigation has been the transient analysis of the Three Mile Isl and Unit 2 pressurizer the methodology is applicable to PWR pressurizers in general. The model includes a detailed representation of the surge line and pressurizer vessel. The surge line is modeled using a one dimensional Eulerian (spatial) mesh description. The spatial and time discretization of the fluid conservation equations is consistent with the extended implicit continuous-fluid Eulerian (EICE) method for thermal/hydraulic calculations. The pressurizer model consists of a uniform pressure, nonequilibrium system, made up of three control volumes and is based on a rigorous application of the first law of thermodynamics and phenomenological heat and mass transfer laws with empirically determined coefficients. The model has provisions for bulk flashing/condensation, spray, heaters, relief/safety valves, and wall condensation. The surge line and pressurizer models are appropriately coupled and the system of finite-difference equations is solved in an iterative manner using the primary pressure and temperatures as boundary conditions. Test calculations performed for verification of the proposed model (PRSZR) yielded results which were in excellent agreement with the plant data. Sensitivity studies have been performed with the PRSZR code to ascertain the degree to which various features of the detailed pressurizer system model were essential for obtaining accurate preductions of the pressurizer response to severe transients. Potential application for the detail pressurizer model are described and future directions and extensions of this work are discussed.Ph.D.Nuclear engineeringUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/158955/1/8224909.pd