• Gesseneck, Josip Jezic Von
• Vanderborght, Bram
• Naidoo, Diana
• Overmeire, Marc Van
• Lefeber, Dirk
• Caers, Ben

Abstract

One of the main concerns of nuclear energy is the treatment of the nuclear waste and thus technology that decreases waste output and waste half-life is consequently very interesting. This is one of the principal aims of the MYRRHA (Multi-purpose, hYbrid Research Reactor for High-tech Applications) GEN-IV reactor project. As a subcritical reactor driven externally by a high-powered accelerator, MYRRHA will be one of the earliest global demonstrations of accelerator-driven systems (ADS). A major advantage of the ADS, besides its subcriticality, is its transmutation of minor actinide waste. Lead-Bismuth Eutectic (LBE) was chosen as the spallation target and coolant for its high spallation efficiency, having a good heat capacity and reduced impact on the speed of the neutrons. Two in-vessel fuel manipulators (IVFM) operating from under the core with 4 degrees of freedom (DOF) must move the fuel assemblies between the core, storage and ex-vessel fuel transfer positions. The IVFM is thus a critical component of the MYRRHA reactor - it is essential to demonstrate its safe operation in proving the feasibility of the reactor by 2014. The LBE environment presents many technological challenges to fuel manipulation: temperatures of 200°C to 300°C, zero visibility, hydrodynamic forces, corrosion, fast neutron irradiation, and the fatigue of long operating periods. This collaborative doctoral project between the SCK* CEN and the VUB, funded by the AVN, supports the development of the IVFM from a safety approach, with the objectives to form the acceptance criteria for safe fuel operation, the design and operation methods to reach these, and adequate tests to validate these methods. Within the framework of the national legislation and international guidelines, we identify the safety functions of the IVFM and evaluate the adequacy of the design and fault response measures in minimizing the related risks to a tolerable level.We approach the safety analysis of the IVFM by both a deductive bottom-up Failure Mode and Effects (FMEA) and inductive top-down Fault Tree Analysis (FTA).A low-resolution FMEA at the component level allows us to organize the testing, warns us about expected failure modes, and prioritizes component and design adjustments based on predicted effects.The complementary FTA maps out the interesting failure paths leading to the most important top failure events of the IVFM in criticality, heat, and radiation. The fault trees are updated from, and feed back into the tests and design with failure modes (qualitative) and occurrences (quantitative), in an iterative process.

Topics

• impedance spectroscopy
• corrosion
• fatigue
• heat capacity
• Bismuth
• Actinide