After Fukushima Crisis, Hearing on Nuclear Energy Safety via About.com Energy

12 Nuclear Reactors Have Had Meltdowns

After the catastrophic events at Japan’s Fukushima Daiichi nuclear power complex in March 2011, the U.S. Senate conducted a hearing about nuclear plant safety. A senior scientist from the Natural Resources Defense Council (NRDC), Dr. Thomas Cochran, spoke at that event.

Cochran, who taught nuclear physics as the U.S. Naval Academy, explained that 582 commercial nuclear reactors have been built and operated worldwide. Of those, 137 have shut down permanently for various reasons. Twelve have suffered meltdown incidents.

With commercial reactors operating on average just under 26 years each, Cochran calculated that a serious nuclear accident occurs approximately every two years.

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During his Senate testimony, Cochran identified twelve nuclear reactors that have had partial or full meltdown incidents. He listed these reactors:

1. Sodium Reactor Experiment (SRE)
Location: Santa Susana Field Laboratory, California
Reactor Type: Sodium-Cooled graphite-moderated thermal power reactor.
Power: 20 Megawatts thermal (MWt); 6.5 Megawatts electric (MWe).
Began Operating: In July 1957, became first nuclear plant to send electricity to the grid.
Melt Down Occurred: Partial core melt accident between July 12 and July 26, 1959, resulting in melting 1/3 of the fuel.
Shut down: Feb. 1964.

2. Stationary Low-Power Reactor #1 ( SL-1)
Location: National Reactor Testing Station (now Idaho National Laboratory)
Reactor Type: Experimental, gas-cooled, water moderated.
Power: 3.3 MWt; 300 KWe.
Began Operating: Initial criticality March, 1960.
Melt Down Occurred: Improper removal of control rods caused steam explosion, ejecting control rods and the upper control mechanism.
Comments: 3 operators killed, including worker who improperly withdrew control rod.
Shut down: May 1964.

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