Re: "can the fault detection system work fast enough. "
One should remember the Saturn V Launch Vehicle Digital Computer (LVDC):
"The LVDC was capable of executing 12190 instructions per second."
https://en.wikipedia.org/wiki/Saturn_Launch_Vehicle_Digital_Computer#Hardware
Dave
P.S. I worked with a guy who's first job was programming the LVDC. When he retired, 40 years later, I printed out a copy of the LVDC manual and presented it to him.