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Communication Dans Un Congrès Année : 2017

New LOCA and RIA fuel safety criteria in France

Résumé

Based on technical assessment of IRSN, the French Advisory Committee for nuclear reactors (GPR) recommended in 2010 in the frame of the French LOCA rulemaking to examine the validity of the safety requirements related to the two modes of fuel degradation during LOCA (ductile mode and brittle mode) in the light of state-of-the-art of the last thirty years. In particular, a strength-based approach including an additional axial loading to be applied to the fuel rod during the quench phase was accepted. Then, the second GPR meeting on this topic held in 2014 focused on redefining an acceptable safety limit concerning the brittle mode based on the LOCA semi-integral tests developed by JAEA. Especially, IRSN assessed the new ECR criterion proposed by EDF, which is now expressed as a function of in-reactor hydrogen pick-up combined with the historical 1204°C criterion. It was also the opportunity of concluding on the physical phenomena to be taken into account in a new methodology to analyze LOCA. The safety assessment of this method has been made by IRSN in 2015. During RIA, the fuel rods are subjected to a mechanical loading due to thermal expansion of the pellets and increase of internal pressure. The first phenomenon can lead to PCMI clad failure and the second one to clad ballooning up to burst. Based on interpretation of specific integral tests, EDF proposed to revise and complete existing RIA fuel acceptance criteria regarding PCMI-induced clad failure: they are expressed by enthalpy variation and pulse width; their limits depend on hydrogen content. Moreover, EDF developed an approach which aimed at demonstrating that the control rod ejection accident initiated at zero power is the most limiting. Lastly, EDF has developed an approach based on the actual number of failed fuel rods instead of the number of fuel rods experiencing DNB. IRSN reviewed EDF’s proposals and presented its conclusions to the GPR in June 2017
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irsn-04588990 , version 1 (27-05-2024)

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  • HAL Id : irsn-04588990 , version 1

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Stéphanie Graff, Sandrine Boutin, Aude Taisne, Olivier Dubois. New LOCA and RIA fuel safety criteria in France. 2017 Water Reactor Fuel Performance Meeting, Korean Nuclear Society, Sep 2017, Jeju Island (South Korea), South Korea. ⟨irsn-04588990⟩
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