According to an article in yesterday’s Tampa Bay Times:
More than 3,700 tubes that help cool a nuclear reactor at Florida Power & Light’s St. Lucie facility exhibit wear. Most other similar plants have between zero and a few hundred.
How bad could this problem be? According to the Times article:
Worst case: A tube bursts and spews radioactive fluid. That’s what happened at the San Onofre plant in California two years ago. The plant shut down forever because it would have cost too much to fix.
The Nuclear Regulatory Commission usually suggests replacement of steam generators as a condition for license renewal. According to the Times:
In 2007, FPL installed two new steam generators for $140 million, intending them to last until the plant’s license expires in 2043.
Then, with license renewals in hand, Saint Lucie began to fall apart:
In 2009, FPL shut down the reactor for routine refueling. An inspection found that the tubes were banging against the stainless steel antivibration bars, leaving dents and wear spots.
More than 2,000 tubes showed some wear in 5,855 separate places. (A tube can be worn in multiple spots.)
Things only got worse:
In 2011, FPL again shut down the reactor and inspected the tubes. The wear had spread.
Affected tubes: 2,978, up 46 percent from 2009.
Worn spots: 8,825, up 51 percent.
The Tampa Bay Times article also cast a new light on one of the nuclear industry’s standard excuses in incidents involving steam generators, the assertion that steam generation is ‘the non-nuclear side of the plant.’
Nuclear power plants are like very expensive tea kettles. The reactor heats water. The steam generator turns hot water to steam, which powers a turbine, which makes electricity.
The steam generator also uses its thousands of alloy tubes to cool water, which is pumped back to cool the reactor. In that sense, the steam generators are a safety device.
“The tubes need to be very thin to transfer heat, and they need to be very strong to prevent a meltdown,” said (Daniel) Hirsch, (a University of California at Santa Cruz nuclear policy lecturer who reviewed the tube problems at San Onofre and St. Lucie.)
“Steam generators are really critical to safety. It’s not a feature you want to play with.”