The word corrupt is still being put forth in ignorance. If miserly is meant, then say so.

However, replacing rather than 'patching' a reactor means construction of a new structure at a cost of near $1 billion.
Patch repairs done at Fukushima? Please quote reference. Are such repairs normally done in maintenance at nuclear plants? Who does them (if done), the installer or the operator? What is the approval route?

'Patch' repairs are normal on many expensive structures. The 'skin' (outer shell of airplanes) are replaced after a time period and many 'patches' are done over the 30 or so year lifetime of a primry service airliner before it is recycled. There are few major costly structures that aren't repaired over time, rather than being replaced.

Of course some regard all companies are corrupt; this implies that their employees and stockholders are complicit- sometimes many tens of thousands.