Carr High Temperature And High Pressure Test Loop Accident Analysis

Nowadays, in-pile test loops are being used world widely to carry out test of nuclear fuel and material. The safety of the in-pile test loop is related closely to the safety of the test reactor since the accidents of the loop may endanger the safety of test fuel rods or even the test reactor itself. A strict safety assessment must be accomplished for the design and the construction of in-pile test loops, and the accident analysis of test loop is one of the important items.The test of nuclear fuel and materials is one of the most important applications of China Advanced Research Reactor (CARR). A high-temperature and high-pressure test loop is being planed in the construction of CARR application platforms. The loop simulates the operating environment (such as linear power of fuel rod, coolant pressure, flow velocity, temperature and water chemistry, etc.) of PWR for irradiation test of PWR fuel and the material.In this paper, cooperating with the ongoing design of CARR high temperature and high pressure loop, the modeling of RELAP5 code is set up by introducing data of the previous 3×3-2 in-pile test for Qinshan Nuclear Power Plant. Several typical design base accidents including LOCA, LOFA and depressurization accident are analyzed, emphasizing on thermal hydraulic behavior of the test loop. Moreover, the effectiveness of ESFs and the possibility of test fuel damage are also discussed. The result provides the accident analysis foundation for the test loop design, and also provides basic information and data for test loop safety analysis report.The main results of the analysis show that:During LOFA, DNBR is greater than 1.3 and the fuel rods keep intact.When a cold leg break accident occurs (equivalent diameter 10 mm), the safety injection system can put into operation automatically, and the low pressure safety injection system provides a long time cooling. The sensitivity studies of break size show that the accident result is related closely to the uncover time of the active zone. The sensitivity studies of break location show that the cold leg SBLOCA is more serious. Nevertheless, the cladding temperature is lower than 1477K (1204°C), and the test fuel rods are safe.During depressurization accident, the safety injection system can ensure the safety of the test loop and the test fuel rod.