European Project “Supercritical Water Reactor–Fuel Qualification Testâ€‌: Results of Fuel Pin Mock up Tests

Abstract

The main target of the EURATOM FP7 project “fuel qualification test for supercritical watercooled reactorâ€‌ was to make significant progress toward the design, analysis, and licensing of a fuel assembly cooled with supercritical water (SCW) in a research reactor. Within the project, fuel pin mockups of a future fuel qualification test facility were designed and manufactured by Centrum Vأ½zkumu إکeإ¾ (CVR). Following that, it was decided to conduct three different types of tests considering two possible accident scenarios. Simulation of loss of external pressure was the target of Test 1. The autoclave was depressurized as fast as possible from 20 to 1آ MPa by opening the close valve located behind the cooling part of the highpressure part of the loop. Pressure inside the pin was held at a constant value of 20آ MPa by pumping highpressure water via the pin and in parallel via a separate relief valve that was connected directly to the pin using the filling pressure tube. A similar approach was chosen when the opposite case, i.e., loss of internal pressure in the pin, was simulated in Test 2A. Eventually, Test 2A was repeated with modified setup to determine the lower limit of the internal pin pressure (i.e., collapse/buckling of the pin due to external overpressure) more accurately. The presented paper summarizes the results of all three performed tests.