OTTAWA - The Conservative government has quietly committed another $135 million to the development of Atomic Energy of Canada Ltd.'s next-generation nuclear reactor.

The Canadian Press has learned that the latest proposed funding for the Advanced Candu Reactor, or ACR 1000, is part of the $351 million budgeted for AECL in last week's federal budget.

The 2009-10 stipend is the biggest federal subsidy to the Crown corporation since the late 1980s, and the Conservative government won't provide an itemized breakdown of what the money is for.

A spokeswoman for Natural Resources Minister Lisa Raitt says there is no final determination on how the AECL funding will be apportioned.

But according to a preliminary list obtained by The Canadian Press, the cash includes $72 million to decommission two medical isotope reactors at Chalk River, Ont. Those reactors, called the Maples, were scrapped last year because of design flaws after going hundreds of millions of dollars over budget and years behind schedule.

There is also $144 million in the AECL funding "to maintain safe and reliable operations" at the Chalk River laboratories.

Federal funding for development of the ACR 1000 is politically and commercially sensitive. The reactor is currently in the running as an option for Ontario's nuclear generation expansion and most experts believe a successful bid by AECL is critical to the future of the Crown corporation.