some nuclear fuel elements problems stress corrosion cracking of zircaloy-2 tubes under iodine environment

Iodine stress corrosion cracking (I2-s cc) and liquid metal embrittlement (LME) of zircaloy-2 cladding uranium dioxide (uo2) fuel in nuclear reactors are considered as an important fuel elements ' problem . This investigation is, therefore, of particular importance from the economic and nuclear safety point of view. The aim of this thesis was investigate: (1) some factors affecting the susceptibility of zry-2 tubes to I2 - SCC at 340 C. These factors were : a) the tube's metallurgical conditions (recrystallized, Rx, or stress relieved, SR), b- the I2 concentration (1.5-100 mg/cm3), c- coating the tube's inner surface by a layer of oxide , 0.35-1.5 um or graphite, 5 um ), d- fatigue pre-cracking (0.1-0.4 mm crack depth) on the tube's inner surface. e- prior stressing at stresses lower than threshold stress for 24 h holding time.2) the role of liquid Cs (190 mg), liquid cd (12-100 mg) or liquid Cs-cd mixture (247-493 mg) on the embrittlement of SR tubes at, also 340 C