Expansion Joint Bellows Rupture Forces D.C. Cook Nuclear Plant Offline

Indiana Michigan Power—a subsidiary of American Electric Power (AEP)—reported that Unit 2 of its Donald C. Cook Nuclear Plant in Bridgman, Mich., was forced offline on July 6 due to an expansion joint bellows rupture on the unit’s moisture separator reheater.

Although no one was in the area at the time and there were no injuries, an adjacent turbine building exterior wall was damaged when the roughly 48-inch-diameter bellows burst. The component is part of the plant’s secondary steam system, providing nonradioactive steam to the low-pressure turbine.

An Unusual Event, the lowest level alert on the Nuclear Regulatory Commission’s (NRC’s) emergency response scale, was declared at 12:50 a.m. due to the unanticipated incident. The event was terminated at 2:07 a.m. The company said all appropriate notifications to local, state, and federal officials were made.

Unit 2 was shut down manually, with no impact to public health and safety. Unit 1 was not involved in the event and remains in operation at full power.

The NRC resident inspector for the site responded to the plant immediately after being notified. The site inspector and NRC Region III office are independently evaluating the company’s response to the situation and the plant’s assessment of what caused the rupture.

The two units at the D.C. Cook facility (Figure 1) have a combined capacity of 2,155 MW. Unit 1 began commercial operation in August 1975 and Unit 2 in July 1978.

1. D.C. Cook Nuclear Plant is a dual-unit facility located along Lake Michigan’s eastern shoreline. Courtesy: Indiana Michigan Power

Indiana Michigan Power said causal analysis and repair estimates are under development. AEP does not release return-to-service information for generation units, so no estimate was offered on how long the unit will be out of service for repairs.

Aaron Larson, associate editor (@AaronL_Power, @POWERmagazine)

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