Vermont Yankee wants new backup diesel generator
By Susan Smallheer
Staff Writer | October 27,2012
BRATTLEBORO — Entergy Nuclear is seeking state and federal approval to bring in a third backup diesel generator to provide electricity to Vermont Yankee in the event of an emergency station blackout.
The diesel generator would replace Vermont Yankee’s dedicated tie-line to TransCanada’s hydroelectric station in Vernon, which will no longer be available to provide emergency power because of a decision by ISO-New England, which manages the power grid in New England.
Entergy Nuclear spokesman Rob Williams said Entergy had filed permit requests last month with both the Vermont Public Service Board and the Nuclear Regulatory Commission to build the diesel generator, which he said was about the size of a school bus, and would be placed on a concrete pad.
Yankee already has two diesel generators for backup power, but the new generator would be dedicated for the loss of electric service to the plant.
“Entergy believes that the PSB will recognize that the project is essential to insure Vermont Yankee’s continued ability to operate safely,” Williams said. Williams refused to say how much the new generator would cost.
The new backup generator is not related to recommended improvements from the Nuclear Regulatory Commission in response to the nuclear tragedy in Fukushima, Japan, said Neil Sheehan, a spokesman for the NRC.
The NRC will meet with Entergy next month to discuss the project. The Vernon dam won’t be available as a backup source as of Jan. 1.
Lacey Ryan, a spokeswoman for ISO-NE, said ISO was not requiring Entergy to install the diesel generator, despite the changes.
“The changes to ISO New England’s blackstart plan mean that some resources are no longer eligible to provide blackstart service to the region. ISO is not requiring any resource to install diesel generation as part of our revised plan,” she said Thursday.
She said ISO’s plan now called for a “top-down approach,” rather than a “bottom-up” approach toward station blackouts.
According to ISO’s filing with the Federal Energy Regulatory Commission, the switch is necessary to make the New England power grid “more robust” and would lead to faster restoration times on the transmission system.
“Vermont Yankee currently credits the Vernon hydro dam as its NRC-required “station blackout” AC power source because the dam is a “blackstart” facility,” said Sheehan. That means the facility can start up and produce power even if the grid is down. Station blackout refers to the loss of all off-site power sources, and is what occurred at Fukushima, he said.
He said the Vernon hydro dam will no longer be maintained as a blackstart facility at the end of the year. ISO and TransCanada have decided not to maintain it as a blackstart facility and will instead use other, larger plants for that purpose, Sheehan said. As a result, Vermont Yankee will need a new power source in order to continue to meet the NRC requirements for coping with a station blackout.