“…Additionally, the fuel cladding deformation is mainly caused by different phenomena including, cladding irradiation-induced swelling, thermal and irradiation creep induced by fuel-cladding mechanical interaction (FCMI) and plenum pressure. Irradiation swelling in HT9 is marginal and is usually neglected in fuel performance analysis [27]. Considering the ∼10 at.% peak burnup and 75% smeared density for X447/A HT9 clad fuel pins, the FCMI effect is marginal as the fuelcladding contact is still "soft" due to the hot-pressing effect [28], [29].…”