The existing proven PWR technologies are basically utilized for the SMART design. However, it also adopts new and innovative design features and technologies that must be proven through tests, experiments, analyses and/or the verification of design methods.

15.2.2.1 Thermal-hydraulic test

A series of fundamental tests and experiments have been carried out throughout the SMART development phases to examine the physical phenomena related with the specific SMART design concepts. The main purpose of these experiments was twofold: to understand the thermal hydraulic behavior of the specific design concepts and to obtain fundamental data to be used, in turn, for further feedback to the optimization of design. Among the experiments conducted, specific SMART design-related experiments are as follows:

• boiling heat transfer characteristics in the helically coiled steam generator tube;

• experiment for natural circulation in the integral arrangement of the reactor system,

• two-phase critical flow tests with non-condensable gases to investigate the thermal hydraulic phenomena of critical flow in the presence of non-condensable gases;

• critical heat flux measurement for 5 X 5 test bundles simulating SMART fuel assembly and out-of-pile mechanical/hydraulic tests for full-scale SMART fuel assemblies;

— Design certificate — Standard design — Experiments	Potable water Electricity
Figure 15.1 SMART development program.

• water chemistry and corrosion tests at a loop facility to examine the corrosion behavior and characteristics of fuel cladding, internal structural materials and steam generator tube materials at reactor operating conditions;

• experiments on wet thermal insulation to determine the insulating effects for the internal pressurizer (PZR) design and to derive a heat transfer coefficient for the design;

• experiments on phenomena and characteristics of heat transfer through the condensing mechanism of the heat exchanger inside PRHRS tanks.

Brief introductions to the typical tests and experiments implemented to verify the

SMART design characteristic are given below.