Percentage isn't the issue. Diablo Canyon Nuclear Power Plant provides the base power usage, which isn't the issue that's causing the blackouts.
Looking at raw percentage numbers for blackouts is wrong because this is an issue of not having enough capacity during peak, which nuclear doesn't solve.
The issue that is causing the problems is peak demand hits around 5:30 pm....exactly at the same time when solar supply is dropping rapidly. We need natural gas peaker plants that basically fire up to bridge the gap during the night.
Every now and then we might get bailed out if wind is strong that day but that's not something you can build a reliable grid on.
Ercot had this problem last year WRT to over-reliance on wind generation capacity. At one dire point we had 90 minutes of $9/KWh rates and the utility was looking to roll blackouts. I paid $200 for 1 day of electricity and I pulled my breaker about halfway through the worst part. I know people who got hit with nearly 4 figures for a single day of usage.
I don't have problems with renewable energy in principle, but until we have practical storage capabilities or other alternatives, it seems like we need to keep most of the less desirable forms of generation capacity around. I do not think it is acceptable to roll blackouts until we have something like a tesla powerwall in every electricity consumers' premises. We should never compromise on grid quality in pursuit of environmental objectives. The 2nd order consequences of an unreliable grid could have even more grave environmental impact than driving the grid with a coal plant (i.e. every business & homeowner on earth starts buying carbon-intensive generators or lithium batteries due to grid stability problems).
Decommissioning nuclear capacity seems like a massive mistake in general, but I understand the geology is potentially subpar in this specific case. Is it technologically infeasible to produce earthquake-proof nuclear power plants? Or, at least plants that would be guaranteed fail-safe under any seismic condition?
It is politically infeasible to do anything with Nuclear power but the technology potentially exists (eg thorium reactors). In this era where punditry is as good as expertise, however, nuclear power plants that failed safe would be looked as the "unsinkable" Titanic was, in hindsight. On top of that, the Fukushima nuclear disaster set the nuclear industry back decades.
Looking at raw percentage numbers for blackouts is wrong because this is an issue of not having enough capacity during peak, which nuclear doesn't solve.