DEVELOPMENT OF SCOPING METHOD FOR NATURAL CIRCULATION LEAD COOLED SMALL MODULAR REACTOR

摘要

This paper deals with the development of a scoping method that can automatically generate a design variable range of natural circulation liquid metal in a small modular reactor. From the performance requirements based upon a Generation Ⅳ system roadmap, the constituting structure materials are chosen and operable conditions are compiled based upon the literature data. Making use of ASME codes and standards, applicable geometry sizing rules on the constituting components were developed to keep the integrity of the system during its lifetime. To quickly generate critical core dimensions out of the given unit cell information, an adjustment relation that connects the critical geometry from one-group diffusion theory and that from the MCNP code is built and used throughout the process. For the selected unit cell dimensions, burnup calculations are carried out to see that the cores can generate the designed amount of energy over the reactor lifetime. To obtain steady state operating conditions from the generated designs, an in-house one-dimensional thermo-hydraulic system analysis code was developed utilizing a momentum integral model and finite element numerical methods to treat the non-uniform descritization of temperature nodes with combined convection and conduction equation of the liquid metal coolant. Utilizing a random method, sizing criteria, and in-house analysis and design codes, an automated scoping methodology was developed. The methodology is applied to a nitride fueled integral lead cooled system to generate the design scopes that satisfy the given constraints and the effect of different constraints are evaluated.