Numerical study of hyperstoichiometric fuel creep (UO2+x) in fuel clad interaction of WWER1000. (November 2019)

• Record Type: Journal Article
• Authors: Safari, M.; Aghaie, M.; Minuchehr, A.; Allahyarizadeh, Gh.
• Is Part Of: Annals of nuclear energy. Volume 133(2019)
• Page Start: 950
• Page End: 959
• Publication Date: 2019-11
• Subjects: Fuel pellet -- Densification -- Swelling -- Fuel creep -- WWER1000 -- Hyperstoichiometric fuel (UO2+x); Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2019.07.040
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: Thermomechanical behavior of hyperstoichiometric fuel pellets (UO2+ x ) is studied. Fuel swelling, densification, thermal stress and creep are numerically considered. PCIs for yUO2 +(1 − y)UO2+x fuel pellets are calculated. It is found by increasing the amount of x and 1-y, the PCIs will occur in lower burnup. Abstract: Nuclear fuel is faced with extreme thermomechanical environments during its operating time. In this period, fuel mechanical response is deeply influenced by inherent heterogeneous microstructures, dependent on stress and temperature. Under the reactions occurring inside the reactor, the fuel crystal will change, and the UO2 will be UO2± x . Creep as a slow deformation process, strongly affected by this irradiation. Indeed, the hyperstoichiometric crystals effect the creep rate and mechanical stresses. In this article, the thermomechanical behavior of WWER1000 fuel pellets considering the hyperstoichiometric fuel (UO2+ x ) is studied. Fuel swelling, densification, thermal stress and creep are numerically considered and pellet clad interactions (PCIs) are evaluated. For validating the model, the results for pellet clad interactions are compared with experimental data. The hyperstoichiometric study of fuel cladding mechanical interaction in WWER1000 shows advancement of mechanical interaction during fuel burnups. It is found while the fuel and clad interaction occurs in 50.8 MWd/kgU for UO2, by increasing the amount of x and hyperstoichiometric fuel in the pellet, the pellet clad interactions will occur in lower burnups. These advancements for several hyperstoichiometric fuels are calculated and results are discussed.