Method and Implementation of Geometric Optimization and Salt Selection of Molten Salt Reactors.

Abstract

A concerted effort is being coordinated among many developed countries to advance new nuclear power systems for commercial deployment. This project is called the Generation 4 International Forum. Of the design categories receiving significant attention is Molten Salt Reactors (MSRs). A shared feature is the use of molten salts at high temperature and low pressure to remove heat from the core. There are many viable MSR design configurations and current designs vary considerably, not only in the general design concept but within design concepts as well. The primary objective of this study is to optimize, on a cost basis, the salt composition and key geometric parameters of MSR design concepts. A novel framework is developed to relate reactor design/construction conditions as well as specific configuration parameters to cost. The evaluation is broad in scope and is therefore divided into several metrics of performance, direct cost, waste, safety, proliferation, modularity and feasibility (technical difficulty). Two reactor classes are examined, the salt-cooled, pebble-bed Fluoride High-temperature Reactor (FHR) and the graphite-moderated, circulating-fuel reactor. Both design evaluations involve numerous analyses to generate data used in the evaluation, such as the calculation of temperature reactivity feedback coefficients and heat exchanger size optimization. The FHR analysis includes maximum fuel temperature calculations and depletion simulations that aim to model on-line refuelling. The circulating-fuel reactor analysis includes the use of novel methods to optimize the xenon removal rate and optimize the salt channel pitch. The cost evaluation was executed with both fixed values and probabilistic distributions applied to many consequential inputs. The results obtained using fixed values provide useful insights into the effect design parameters have on cost, while uncertainty analysis provides estimates of cost uncertainty, both overall and between configurations. Sensitivity analysis breaks down the cost uncertainty into component parts. This work aims to deepen the understanding of the costs and trade-offs associated with numerous design characteristics.