The Province announced recently it was giving the three companies bidding to build the reactors the extra time to submit proposals. The new deadline is Dec. 31 of this year and the winning vendor will be chosen by the end of March, 2009.

The submissions were originally to be in by mid-September.

The deadline for the reactors to be in-service remains July 1, 2018.

Lorne Burger, a spokesman for Infrastructure Ontario, said even with the extended time-line for proposals, "the overall time-line is the same. It's still the same in-service date.

"There's time early on to add three months. It won't affect the overall time-line," Mr. Burger said.

The provincial government announced in mid-June the two reactors would be built next to the Darlington nuclear station. The successful bidder will construct the units and Ontario Power Generation will operate them.

Three companies are in the bidding -- AREVA NP, Westinghouse Electric Company and Atomic Energy Control Limited, builder of the Candu reactors used at the Pickering and Darlington stations.

The extension was sought by the three vendors, Mr. Burger said. "They've asked for more information regarding the procurement terms.

"They want to discuss the more technical parts. They want to understand the risk we want them to take on," Mr. Burger said.

The final cost of the two units won't be known until the final negotiations with the winning bid, he said.

Under the procurement project, the builder of the units would be responsible for having the reactors built on time. The builder would be responsible for any costs if the construction extended beyond the start date.