From 2 November 2020, the autumn semester 2020 will take place online. Exceptions: Courses that can only be carried out with on-site presence.
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151-2039-00L  Beyond-Design-Basis Safety

SemesterAutumn Semester 2017
LecturersH.‑M. Prasser, L. Fernandez Moguel, B. Jäckel, T. Lind, D. Paladino
Periodicityyearly recurring course
Language of instructionEnglish
CommentStudents registered at ETH Zurich have to enroll to this course at ETH. EPFL students can enroll to this course directly at EPFL.


AbstractComprehensive knowledge is provided on the phenomena during a Beyond Design Bases Accident (BDBA) in a Nuclear Power Plants (NPP), on their modeling as well as on countermeasures taken against radioactive releases into the environment, both by Severe Accident Management Guidelines (SAMG), together with technical backfitting measures in existing plants and an extended design of new NPP.
ObjectiveDeep understanding of the processes associated with core degradation and fuel melting in case of sustained lack of Core Cooling Systems, potential threats to the containment integrity, release and transport of active and inactive materials, the function of the containment, countermeasures mitigating release of radioactive material into the environment (accident management measures, back-fitting and extended design), assessment of timing and amounts of released radioactive material (source term).
ContentPhysical basic understanding of severe accident phenomenology: loss of core cooling, core dryout, fuel heat-up, fuel rod cladding oxidation and hydrogen production, loss of core coolability and, fuel melting, melt relocation and melt accumulation in the lower plenum of the reactor pressure vessel (RPV), accident evolution at high and low reactor coolant system pressure , heat flux from the molten debris in the lower plenum and its distribution to the lower head, RPV failure and melt ejection, , direct containment heating, molten corium and concrete interaction, in- and ex-vessel molten fuel coolant interaction (steam explosions), hydrogen distribution in the containment, hydrogen risk (deflagration , transition to detonation), pressure buildup and containment vulnerability, countermeasures mitigating/avoiding hydrogen deflagration, formation, transport and deposition of radioactive aerosols, iodine behavior, plant ventilation-filtration systems, filtered venting to avoid containment failure and mitigate activity release into the environment, containment bypass scenarios, source term assessment, in-vessel and ex-vessel corium retention, behavior of fuel elements in the spent fuel pool during long-lasting station blackout, cladding oxidation in air, discussion of occurred severe accidents (Harrisburg, Chernobyl, Fukushima), internal and external emergency response. Probabilistic assessment and interfacing with severe accident phenomenology.
Lecture notesHand-outs will be distributed
Prerequisites / NoticePrerequisites: Recommended courses: 151-0156-00L Safety of Nuclear Power Plants plus either 151-0163-00L Nuclear Energy Conversion or 151-2015-00L Reactor Technology