Ben,

 What is the expected lifespan of such reactors? 

If you look at the chart near end of article you will see that current record for oldest plant is 50.  Below are 4 other plants ( and ages) shutdown in 2019 that I did not mention in the article

• Chinsan-2 -  41 years
• Genkai-2 - 39 years
• Pilgrim-1 - 47 years
• ThreeMile Island-1 - 45 years

Also, keep in mind there is a difference between how long something can survive vs how long it can run economically. So, for example in Spain, when analyzing when to close older plants - a maximum amount of $spend was agreed upon by plant owners.

Power firms agree on route to close Spain's oldest nuclear plant

A disagreement between Almaraz’s owners, Iberdrola, Endesa and Naturgy, over how much to invest to keep the plant running rumbled on close to a March 31 licence renewal deadline, putting the plant at risk of an earlier closure. 

The firms will now apply to keep the site’s two reactors running until 2027 and 2028 respectively, on condition they will spend no more than 600 million euros on them, three sources with knowledge of the talks said.

Note: these two reactors will be 46 and 45 years old when they retire.

The Almaraz plant in Western Spain is the first nuclear reactor slated for closure in a calendar which foresees all seven in the country going offline between 2027 and 2035.

The oldest plant in Spain would be 50 by 2035.

Bob,

then present no evidence one of those plants doesn't function as well as the day they went online.

I had a quote in my article that used the word "decrepit" in describing the Korean plant that is closing.  How is that "no evidence"?

        "The early closure decision was made amid the falling operational rate and the growing maintenance costs for the decrepit reactor."

You can look up the specific operational details here.  Evidence.

More evidence. Here is a comment about Swedish plant closing:

Ringhals 2 was put into commercial operation in 1975, and ever since then has led an eventful life, with both ups and downs. Among other things, the plant has had its steam generators and control room replaced, survived a fire and had the bottom plate of its reactor containment renovated

You can look up operational data here.

Good to hear that Korea is replacing older, smaller  reactors with newer ones. But doesn't that just reinforce my point that older reactors are shutting down.  If, as you say, these reactors can easily run till they are 80-100 years old if properly maintained - why are they being replaced? Why not just keep them and add new plants as well.  You are proving my point.

From linked Korea article:

Under a long-term energy plan to lower dependence on fossil fuels and nuclear power while using more sustainable energy sources, the South Korean government planned to retire 11 out of 24 nuclear reactors in the country by the end of 2030.

You said:

even generating more than their rated capacity factor. Has that ever happened at a solar farm or a wind farm? Didn't think so.

Happens all the time... where have you been? Companies are building entire businesses around repowering wind and solar. Plus now they are throing in storage as well.

Example 1

The Public Service Commission has okayed the re-power plan. Under it, Ashtabula Wind will replace existing turbines with newer, more power-generating models, that will increase its capacity from 148.5 megawatts to 160.4 megawatts. The turbine blades will also be larger.

Example 2

Completion and operation of the Summit Wind Project is planned for late 2020. The repowering project will replace 569 one-hundred-kilowatt turbines with 23 modern turbines.

Example 3 - Solar

OCI Solar power has repowered a portion of their 39.2MWac / 49.4MWdc Alamo 1 solar power plant located in Bexar County, Texas. The plant has been upgraded to Array Technologies trackers and bifacial solar modules. Existing inverters, manufactured by Kaco New Energy, concrete foundations, and balance of system gear were left in place.

And now, a $20 billion revenue stream is arising – upgrades of racking, inverters, and solar modules via the process of repowering these plants – that seeks to maximize the amount of electricity that can be delivered through already existing interconnection approvals.