The performance and long-term operational integrity of containment sys
tems and components is being challenged as many of the world's nuclear
plants progress into the second half of their design lives. As time i
n service increases, so does the likelihood of component failure due t
o long term degradation. By observing trends in containment degradatio
n, potential weaknesses can be anticipated and corrected, minimizing i
nterruptions in operations, increasing safety and improving the plant'
s life extension outlook. One such trend, affecting containment penetr
ation flexible metallic bellows that are subject to cyclic loading, is
beginning to appear in some BWR plants.