10 Worst Civilian Nuclear Accidents in History


Image: John G. Kemeny
Cleanup after the nuclear accident at Three Mile Island in Pennsylvania

In 1945, towards the end of World War Two, two different atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki. Ever since then, the word “nuclear” has evoked a mixture of fear and suspicion in many minds. Moreover, controversy still surrounds nuclear technology, even when it is used for nonviolent purposes – for example, as a source of power. For the doubters, these 10 civilian nuclear accidents won’t be very reassuring.

Image: Nuclear Regulatory Commission
The Davis-Besse Nuclear Power Station

10. Davis-Besse Nuclear Power Station – Ohio, USA

International Nuclear Event Scale Level: 3

Fortunately, the first event on this list didn’t result in dire consequences – although matters could have been very different. On March 5, 2002, a hole the size of a football was found in the pressure vessel head of the reactor in Ohio’s Davis-Besse Nuclear Power Station. Fractured control rod drive apparatus had leaked coolant onto the carbon steel vessel head, corroding the metal until the only thing preventing high-pressure reactor coolant from escaping was 3⁄8 inches (9.5 millimeters) of stainless steel cladding.

A radiation catastrophe was narrowly averted when maintenance workers noticed the hole. Undiscovered, the breach would probably have meant a massive loss of coolant, which may have led to a nuclear core meltdown. Plant owners were forced to pay $28 million in fines to the US Department of Justice and $5 million to the Nuclear Regulatory Commission.


Image: Idaho National Engineering and Environmental Laboratory
Checking the surrounding area for contamination following the accident

9. National Reactor Testing Station – Idaho, USA

International Nuclear Event Scale Level: 4

Unfortunately, this nuclear reactor accident at Idaho’s National Reactor Testing Station (now the Idaho National Laboratory) did not end as harmlessly as the previous incident in this article. Instead, it brought about the only fatalities from such an episode in US history. On January 3, 1961, a control rod was withdrawn too far out of an experimental reactor named the Stationary Low-Power Plant Number 1 (or SL-1). The result was a core meltdown that led to an explosion of steam, killing three military personnel stationed at the reactor.

The blast was so strong that the SL-1 reactor was jolted more than nine feet into the air. Following the incident, the radioactive isotope contamination was so severe that the three men who died – killed by the blast and not the radiation – had to be laid to rest in lead coffins. Because a report on the accident was not widely publicized at the time, exact details about the explosion became the subject of speculation.