Unit 2 Transformer Failure in 2010 Results in Oil Spill and 2012 NYS DEC Fine

In November 2010 a failure of Indian Point unit 2’s main electrical transformer resulted in a spill of transformer oil into the ground beneath the transformer with some of the oil reaching the Hudson River. Beneath the main transformer sits a containment moat designed to capture and hold transformer oil that could be spilled during a failure. The moat has a concrete and bedrock base and walls and is filled with stone. A flaw in the original construction of the moat, previous to Entergy’s ownership, allowed oil to pass through a gap in the moat.

We since replaced the transformer and repaired a gap in the seal of the moat to help contain possible future oil spillage. We have also added eight pump-out casings to the moat system that will help prevent oil from flowing out of the moat; previously there were two.

Indian Point has multiple transformers on site to change electrical voltage for transmission to external customers or for use onsite. The main transformer changes voltage for transmitting electricity offsite.

In March 2012, Entergy and the DEC agreed to a Consent Order that directed us to pay a $1.2 million penalty for the oil release to the environment.

A previously unidentified gap in a section of the underground moat wall that adjoins the base of the nearby turbine building allowed transformer oil to flow into the ground beneath the turbine building, and eventually to the discharge canal and river.

About 11,000 gallons of the 19,600 gallons of oil contained in the transformer before its failure were recovered from the transformer and the surrounding underground moat containment system. About 8,600 gallons of oil flowed into a sub basement and ground beneath the turbine building and moat with some reaching the plant’s discharge canal and river.

Transformer Failure and
Resulting oil spill
Click for enlarged view.

Within hours of the transformer failure, environmental mitigation crews were onsite to assess the oil spill and remove and process the oil.

Transformer oil, unlike diesel or crude oil, is clear and light. The oil in the failed transformer contained no PCBs (polychlorinated biphenyls) and its spillage resulted in little or no quantifiable adverse consequence to the environment.

We believe, however, that any spill of transformer oil to the environment is not in accordance with our standards and have moved aggressively to eliminate the potential for a recurrence of oil spillage to the environment.

To help ensure there are no future transformer failures at Indian Point, we have proactively replaced part of a similar transformer manufactured by the same company and of the same manufacturing vintage as the one that caused the 2010 failure. The cause of the transformer failure was determined to be a manufacturing or design defect. We have reviewed and reaffirmed that our transformer safety monitoring regimen conforms to industry and manufacturer recommended programs.

Replaced transformer and
transformer moat repairs
Click for enlarged view.

Entergy has fully cooperated with the DEC throughout and agreed to pay $1.2 million, with half the money to benefit an environmental stewardship project to be identified by Entergy.

We take our commitment to the environment seriously and accept full responsibility for transformer oil reaching the ground and river.

Next Steps

Entergy continues working with the DEC to ensure the provisions in the Consent Order are met, that possible spills in the below-ground moats associated with site transformers are captured and appropriate measures are taken to mitigate the effects of potential oil spills.

Entergy continues inspections of all moats on site in accordance with provisions in the Consent Order.