M. Frankl , L. Berry , A. Vasiliev , D. Rochman , H. Ferroukhi , N. Diomidis , M. Wittel
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引用次数: 0
Abstract
The Swiss National Cooperative for the Disposal of Radioactive Waste (Nagra) and the Center for Nuclear Engineering and Sciences at the Paul Scherrer Institute (PSI) are investigating how potential long-term changes to the geometry and material composition of the current final disposal canister (BE-ELB) design may affect the neutron multiplication factor (keff) of a canister loaded with PWR spent nuclear fuel assemblies (FAs). Several conservative corrosion scenarios were formulated, modeled, simulated and analyzed using the Monte-Carlo codes MCNP6.2® and Serpent2.2. The corrosion-induced effects, such as the replacement of moderator by magnetite, differ significantly from typical fuel lattice configurations used in reactor or storage pool safety analyses. This paper therefore focuses on underlying physical phenomena causing the observed keff changes, including analyses of neutron currents and spectra, the ‘6-factor formula’, and the sensitivity of keff to specific regions, materials, and nuclides. These analyses showed the canister wall and the corrosion product magnetite to act as a heavy reflector, enhancing the backscattering of neutrons in the epithermal and fast energy ranges. Furthermore, the critical role of the water distribution in all the potential scenarios was revealed. Water inside the FAs clearly increases reactivity by moderation, water outside the remainders of the steel basket, however, has an inhibiting effect on neutron multiplication. All simulation results heavily depend on the specific preliminary ELB design. To that end, the results of this study can help to optimize the ELB design and the Swiss concept for the final disposal of high-level radioactive waste.
期刊介绍:
Nuclear Engineering and Design covers the wide range of disciplines involved in the engineering, design, safety and construction of nuclear fission reactors. The Editors welcome papers both on applied and innovative aspects and developments in nuclear science and technology.
Fundamentals of Reactor Design include:
• Thermal-Hydraulics and Core Physics
• Safety Analysis, Risk Assessment (PSA)
• Structural and Mechanical Engineering
• Materials Science
• Fuel Behavior and Design
• Structural Plant Design
• Engineering of Reactor Components
• Experiments
Aspects beyond fundamentals of Reactor Design covered:
• Accident Mitigation Measures
• Reactor Control Systems
• Licensing Issues
• Safeguard Engineering
• Economy of Plants
• Reprocessing / Waste Disposal
• Applications of Nuclear Energy
• Maintenance
• Decommissioning
Papers on new reactor ideas and developments (Generation IV reactors) such as inherently safe modular HTRs, High Performance LWRs/HWRs and LMFBs/GFR will be considered; Actinide Burners, Accelerator Driven Systems, Energy Amplifiers and other special designs of power and research reactors and their applications are also encouraged.