Fuel Pin Behavior up to Cladding Failure under Pulse-Type Transient Overpower in the CABRI-FAST and CABRI-RAFT Experiments

Abstract

In the CABRI-FAST and CABRI-RAFT programs within a collaboration with the Institut de Radioprotection et de Sûreté Nucléaire (IRSN) and Forschungszentrum Karlsruhe (FZK), five pulse-type transient overpower tests were performed in order to study fuel pin behavior and failure condition in the Unprotected Loss-of-Flow (ULOF) accident. In these tests, two types of low-smear-density fuels irradiated in the French Phénix reactor at different burn-up levels were used so that an experimental database extension from the former CABRI-1 and CABRI-2 programs can be obtained. Pin failure took place in three of these tests giving information on the failure threshold. In two tests, no pin failure took place and useful information related to the transient fuel behavior up to failure and failure mechanism was obtained. These test results were interpreted through detailed analysis of experimental data and PAPAS-2S code calculations. In these calculations, pretransient fuel characteristics obtained from the sibling fuels were reflected, such that the uncertainty of the boundary condition can be minimized. Through the comparison among these tests and formerly existing CABRI tests, generalized understanding on the transient fuel behavior was obtained. It was concluded that the low-smear-density fuel mitigates cavity pressurization, thereby enhancing the margin-to-failure. It was also understood that this failure-thresholdenhancing capability is dependent on the type of transient.

Summary Report for U.S. and Japan Bilateral Collaborations (FY2019)

“…Refs. [Perez-Martin 2013], [Fukano 2009], [Fukano 2010], [Charpenel 2000], [Papin 2012] describe these tests and the experimental data used in this report. The two of the tests adopted has VIGGEN-4 fuel pins (see Table 4.3.1.1 ) and three of the tests used SCARABIX fuel pins (see Table 4.3.1.1).…”

Validation study of SAS4A code for the unprotected loss-of-flow accident in an SFR

“…designed to precisely model the IP event progressions and was developed by the experimental knowledge obtained from various in-pile experiments in the French CABRI (Heusener et al, 1990;Haessler et al, 1990;Sato et al, 2004;Fukano et al, 2009;Fukano et al, 2010) and U.S. TREAT (Wright et al, 1990;Fukano, 2013) reactors.…”