Two nuclear power plants owned by New Orleans-based Entergy were forced to shut down over the weekend following serious operating problems, including a radioactive leak at one plant in Vermont.

Those troubling incidents come on the heels of an electrical explosion at NRG's South Texas nuclear plant last week, and a Friday incident at Progress Energy's Shearon Harris plant in North Carolina that caused the plant to momentarily lose cooling to the reactor core.

The problems all occurred within days of President Obama's post-election press conference in which he promoted restarting the U.S. nuclear power industry. His remarks came after heavy spending by the nuclear power industry during the recent election cycle.

Entergy's Vermont Yankee plant was shut down Sunday evening after radioactive water escaped from a pipe leading to the reactor. Half an hour earlier, a transformer exploded at Entergy's Indian Point plant in New York, causing a shutdown of that facility.

Both the Vermont Yankee and Indian Point plants are among the 20 U.S. nuclear power plants that have been plagued by leaks of radioactive tritium. The Vermont plant has also been afflicted in recent years by a fire in the main transformer and the collapse of a cooling tower due to structural corrosion and rot. Vermont state Sen. Pete Shumlin -- the state's newly elected Democratic governor -- led an effort to get the plant closed on schedule in March 2012, a plan his Vermont Senate colleagues approved last February.

The incident at the Shearon Harris plant near Raleigh, N.C. occurred during an outage to replace the electrical generator with one purchased from the disaster-stricken Three Mile Island nuclear plant in Pennsylvania. Even when a nuclear plant is off line, it must continue cooling the reactor core and spent fuel pools.

"This is likely to trigger a special investigation by the [Nuclear Regulatory Commission], and could result in a costly extension of the plant's down time," said Jim Warren, executive director of the N.C. Waste Awareness and Reduction Network, a nuclear watchdog group.

The Shearon Harris facility is also among the nuclear plants that have leaked radioactive tritium to the environment.

And on Nov. 3, less than two hours before the press conference where Obama discussed the nuclear industry restart, there was an explosion in an electrical breaker inside the protected area at New Jersey-based NRG's South Texas nuclear power facility near Bay City. The cause of that incident, which fortunately did not result in a fire, remains under investigation.