Sensitive government documents left behind at a CTV News bureau reveal Ottawa has poured far more money into the aging Chalk River nuclear reactor than the public has been told.

The binder of documents was left nearly a week ago at CTV's Ottawa bureau by either Minister of Natural Resources Lisa Raitt or one of her aides. Some of the papers are clearly marked "secret."

Ontario's Chalk River reactor supplies at least one third of the world's medical isotopes, which are used in diagnostic tests for some forms of cancer. Atomic Energy of Canada Ltd. shut down the reactor last month because of a heavy water leak.

In documents headlined "Background for discussion with chair of Atomic Energy Canada," the government lists funding for the Crown corporation at $351 million for 2009-2010. That figure was in the January budget.

However, it also lists $72 million to "maintain the option of isotope production." The public 2009 budget does not specifically mention funding for isotopes.

The documents also include a hand-written note that lists total funding for Atomic Energy of Canada, Ltd. since 2006 at $1.7 billion, and then a talking-point memo to characterize the spending as "cleaning up a Liberal mess."

The Conservative government plans to privatize AECL's nuclear reactor division in order to boost sales of its CANDU reactors, as Ontario weighs whether to buy two new power plants.

Publicly, Ottawa has downplayed Ontario's interest in the sale of AECL's Candu division. But included in the binder is background information for a May 25 meeting with Glenna Carr, who chairs the board of directors for AECL: "The government continues to support AECL's bid in Ontario, but the announcement will probably raise questions about this support. We will have to manage this very carefully."

Other documents highlight cost increases for AECL that have not been made public. In one document headlined "Discussion with CEO Hugh MacDiarmid, CEO of Atomic Energy Canada," it lists $100 million in supplementary funding to keep it solvent.

That figure includes cost increases to refurbishing Ontario's Bruce Power reactors and cost-overruns at Candu reactors around the world, according to the documents.

And in papers headlined "Minister Raitt's Discussion with Ontario Minister of Energy George Smitherman," it appears that AECL is far behind schedule on refurbishing two of the Bruce reactors: "Bruce 1 reactor 324 days late," and "Bruce 2 reactor 433 days late."