Evaluation of scale-up capability of best estimate code application on China advanced Gen-III reactor

Abstract

The Code Scaling, applicability, and Uncertainty method states the code’s capability to scale up processes from test facilities to full-scale nuclear power plants needs to be validated and evaluated. The reason for this validation is that it is infeasible (or cost prohibitive) to perform meaningful experiments at full scale and the ability of numerical tools designed to simulate the performance of nuclear reactors can be proven only at reduced scale.

ACME is an integral test facility, which is designed to study the behavior of China Advanced Pressurized Water Reactor (PWR) under accident conditions. The RELAP5 code is the best estimate thermal hydraulic system code for performing nuclear power plant safety analysis. This study validates the code scale up capability for application on China Advanced PWR. Firstly, we propose a new evaluation scheme, which is to take the realistically constructed test facility as a reference and scale up its numerical model to the size of a prototype power plant strictly according to scaling laws. This method, on one hand, ensures that the numerical model of the test facility and the scale up numerical model maintain consistency in node division. On the other hand, it avoids the influence of engineering deviations. Secondly, a numerical model for the prototype power plant scale was established based on the ideal scaling laws. After that, a 2-inch cold leg break accident test was simulated on two different scale numerical models, and the calculation results were compared with experimental data. The RELAP5 scale up capability to predict the accident phenomenon of China Advanced Gen-III PWR was evaluated using both qualitative and Fast Fourier Transform Based Method (FFTBM) quantitative methods.