The two partially completed VVER 440 reactors near Cienfuegos, Cuba are in a class by themselves, however. Soviet advisors reportedly told Cuban officials they could not guarantee that valves installed in the first reactor's emergency cooling system would function under certain conditions. In tropical areas, such machinery must be stored in climate- controlled facilities to avoid serious corrosion and other damage. In a number of cases, equipment designed for one specific function has been used for other purposes when the appropriate components were unavailable . This sort of jerry-rigging increases the chances of systemic failures.
Construction supporting primary reactor components contains numerous structural defects.
The first reactor's dome would not be able to contain overpressures associated with meltdown conditions. As many as fifteen percent of the 5,000 welds joining pipes used in the reactors' auxiliary plumbing system, containment dome and spent fuel-cooling system are known to be flawed . According to Vladimir Cervera, the senior engineer responsible for overseeing quality control at the Juragua reactor, X-rays showed welded pipe joints weakened by air pockets, bad soldering and heat damage. Bear in mind that, if a single weld in a U.S. reactor were suspected of being defective, the Nuclear Regulatory Commission would suspend its operations. What is more, Cuban intelligence services are reported to have destroyed x-ray imagery and other documentation concerning safety violations, making corrective action problematic.