Owners of the Caithness power plant in Yaphank stressed the facility's "zero-accident" operating record and safety measures Monday in the aftermath of a power-plant explosion Sunday in Middletown, Conn., that killed five people and injured more than two dozen.

Both the Caithness plant, which began supplying energy last August, and the Connecticut-based Kleen Energy Systems plant, which was under construction, use the same efficient "combined cycle" technology and turbine equipment made by Siemens.

PHOTOS: Conn. power plant under construction blows up

In a statement released Monday, Caithness noted that its facility has been operating since Aug. 1, "recording a zero accident, post-operational safety record." The Kleen Energy plant was not yet operating and was expected to come online later this year.

While he declined to comment on the accident, Ross Ain, president of Caithness Long Island, Llc, said in a statement the Yaphank plant is a "safe, modern, clean, natural gas-fired plant which was built strictly in accordance with federal, state and local safety standards."

Caithness said inspections and startup operations on the gas-delivery system into its plant were conducted by Siemens and gas-supplier National Grid in December 2008 and January 2009, "without incident."

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The plant has natural-gas detectors, pressure-relieving devices, automatic shut-offs and advanced fire-protection and suppression systems, Caithness said. Full-time staff routinely inspect systems.

The Kleen Energy plant was 96 percent complete when it exploded Sunday morning while workers were purging natural gas lines. Purging evacuates the pressurized gas from supply lines, releasing it into open air or another gas line.

LIPA vice president Paul DeCotis said the authority, which buys most of the capacity from the Caithness plant under a 20-year, $1.6-billion contract, said Caithness underwent similar a purging, without incident. "When Caithness went online they had to blow out lines to get the gas through," DeCotis said. "You only do it once."

During its testing phase last summer, the Caithness plant once emitted noises that worried at least one local resident. The Yaphank man, John McConnell said one Sunday night last summer he heard a "loud rolling noise like a jet plane" coming from the plant a mile and a half away. McConnell, who is one of a group of residents who unsuccessfully sued to block the plant, said he notified local code officers and his legislators, to no avail.

Caithness spokesman Don Miller said any sounds that came from the plant were part of normal testing.

There was at least one glitch during the testing phase, related to cooling fan blades, LIPA said last summer. Miller said he was unaware of it.

PHOTOS: Conn. power plant under construction blows up