Clean energy journalism for a cooler tomorrow

Old reactor safety concerns are new again

The reactor design in use at the Fukushima Daiichi plant in Japan - as well as six other plants in the Midwest - has been questioned by safety experts for decades.
By Ken Paulman

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Diagram of the Fermi 2 nuclear reactor, via NRC.

The New York Times reports today that the reactor design used in Japan’s Fukushima Daiichi plant — as well as in 16 other nuclear plants in the U.S. — has been dogged by safety concerns for decades.

The G.E. Mark 1 reactors use a weaker containment vessel than other types of reactors, the Times reports — making them cheaper, but also at potentially higher risk of failure. Safety officials, as early as the 1970s, were raising alarms about the potential for an explosion and rupture in the containment units from a buildup of hydrogen.

Of the 16 plants in the U.S. that use the Mark 1 containment system, six are in the Midwest:

Cooper Nuclear Station in Brownville, Nebraska
Dresden Nuclear Power Station in Morris, Illinois
Fermi 2 in Newport, Michigan
Monticello Nuclear Generating Plant in Monticello, Minnesota
Quad Cities Nuclear Power Station in Moline, Illinois

For their part, G.E. defends the reactor design, telling the Times ​“there has never been a breach of a Mark 1 containment system.”

UPDATE: Reuters interviewed a G.E. engineer, who said he resigned 35 years ago over concerns about the safety of the Mark 1 containment system.

Ken Paulman is the director of impact at Canary Media. He was previously the founder and director of the Energy News Network, which merged with Canary Media in 2025.

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